Hello everyone, im 22 and have a pro-street '85 s-10 that i am planning to build a 355 for.  I already have a good 4-bolt main 350 block and i plan on the .030 bore... I plan on buying a new rotating assembly and pistons to match my .030 over bore, going with the GM Vortec heads...my questions are....
What compression can i run and still run pump gas?

What lift/duration/specific brand cam is best to use to get good streetable hp with a somewhat thumping sound.

I know my intake has to match my vortec heads but what style do i need to get for my application and i was thinking a 750cfm carb, is this too big?

Is 400 hp a reasonable expectation for this sort of application or am i completely wrong?

I know this is a lot of questions from a new member but any help with this would be greatly appreciated!
Thanks in advance!!  

What compression can i run and still run pump gas?

This question has been asked so many times that you will find a wide array of answers to it. There are conservatives and there are radicals. Some say run 9.25:1 with iron heads and 89 octane and have some wiggle-room to run plenty of timing, some others say 10.5:1 on premium and be on the ragged edge...

If you actually start measuring the volume of everything in the combustion chamber you will soon realize that static compression has a good amount of luck involved as well. As chambers vary widely, valve reliefs are commonly underestimated and piston to deck clearance cannot be helped with some low-buck machine shops, amongst other "tolerances." I realize you probably won't take the time to accurately dial-in your static compression so just shoot for a middle of the road number and hope that it's around there.

What lift/duration/specific brand cam is best to use to get good streetable hp with a somewhat thumping sound.

I'm a Comp Cams guy, but of course there are many that disagree and will say NEVER to use this brand of camshaft. Those usually are the type that had one go bad and would rather blame the camshaft company than realize that THEY did something wrong. When you build a high performance engine something that is of the highest priority is the camshaft. I cannot put enough emphasis on flat tappet camshaft break-in, it's a growing problem and it can cost a lot of money if something goes wrong. If a flat tappet camshaft "goes out" the lifter is eaten away by the camshaft incredibly fast and this metal is obviously going to ruin an engine's bearings.

About duration, it's very application specific. Textbook advice is to contact several camshaft manufacturers and get their advice. This is not a bad idea for a novice, it at least gives you a general idea but remember that tech guys on the phone really aren't that informed. A lot of comes down to your own choice but it's not a bad plan to get some other opinions first even if they aren't coming from professional engine builders.

If you give a detailed explanation of your ride and your future plans there are many here that would give their opinion on what they think would work best. But like I said take these opinions with a grain of salt, it is an internet message board, not a engineering grad school seminar.

I know my intake has to match my vortec heads but what style do i need to get for my application and i was thinking a 750cfm carb, is this too big?

Even though it's commonly misunderstood you can't have too much airflow (CFM) in a carburetor, that is not what "overcarbs" an engine. Rather, what creates the "overcarb'd" symptoms is poor fuel atomization at low speeds. This arises from having too much area available to the engine and a booster design that isn't sufficient, by area I mean venturi diameter. Because common carbs aren't spec'd by their venturi diameter you can use the classical formula {airflow requirement = (C.I.D. x max RPM / 3456) x Ve%} as a guideline but feel free to use a larger carb than the formula suggests (just don't use less). Remember, things like annular boosters, dual plane intakes, and vacuum secondary carbs allow more carburetor CFM to be used.

Is 400 hp a reasonable expectation for this sort of application or am i completely wrong?

400 horsepower is very possible but don't get caught up in horsepower numbers. Get a combination tailored to your vehicle well and build something you enjoy driving or that does what you want it to do. A dyno is a design tool, it's not the real thing. That 400 horsepower figure you're referring to is probably going to be achieved on a flywheel dyno with few of the engine's accessories installed, this is also at a set atmospheric condition. Now consider how the driveline affects how much power (and when that power) is applied to the ground and how other required accessories absorb power, and how much atmospheric conditions can change to a street rig and you realize those dyno numbers mean very little.

I know this is a lot of questions from a new member but any help with this would be greatly appreciated! Thanks in advance!!

Obviously, I don't mind a few questions as I wrote a short book. Feel free to continue to ask them...  

thanks alot for your advice, i know this forum is gonna be very helpful during this build, can't wait to post some finished pics soon!!  Thanks again!  

400 hp with a 350 will be easy.As for overbore,bore your cylinder case to bare minimum to get a good ring seal,as to preserve material for future rebuilds.The few cubic inches you give up will not be not affect power at all.If you have Vortecs then GMPPs Hot cam is a gauranteed 400+ hp,but in MY opinion a little down on bottom end.Compression for pump gas?Figuring on 91 octane I'd say 11:1 max with aluminum heads and a large duration cam,10:1 max with iron and a large duration cam.As for a particular cam,I LOVED my Comp Extreme 4x4 cam in my 400.Part # 12-243-3.480/498 lift with 270-278 adv. duration.I know that doesn't sound very "racy" but that cam makes crazy torque.I ran mine in a 11:1 IRON head 400,1979 k20 4x4 with 35" mud tires with an old granny gear 3spd.I could SMOKE the tires in first(not granny)gear and then grab second a burn for a few more feetCam makes good top end power,too.Down in about 10-14 inches of mud spinnig ALL FOUR tires in HIGH range she'd never bog or miss a beat.Man I miss that truck!I ran long tube 1 5/8 headers/turbo mufflers and the truck had a real noticable lope,but didn't shake the truck so much as too be annoying.As far as compression ratio goes,remember to consider cylinder pressure.High static compression with low duration and little overlap make for high cylinder pressures.Good for building low end torque,but also good for causing detonation.The 400 I told you about could run on 87 octane for runnig the roads,but NEEDED 93 for playing.Good luck with your truck and keep us posted on whats happening  

thanks alot 48olds... i cant wait to start buying up parts for this build as soon as i can afford it!! thanks again!