vortec heads on a 400ci.!!???

hello i'm new here just wanna pik anyones brains for some info now and then.thanks
first of all i'm building a rat rod for this motor 406ci. s10 chassis 9inch rear 38 int. cab sectioned frame for cab,alum. rad/alum. intake 4bbl./3spd 350turbo.
i'm interested in putting vortec heads on my 400 but not sure which ones 305 or 350's i'm not up on these quite yet,its going to be a everyday driver in the summer so high rpm's are'nt a factor just balls when i want it, lo's to mids will be fine. i've driven antique trucks and cars in the past a few performers but nothing serious to get me trouble. so again i know i have to drillout the steam holes before installing them and get some sort of aftermarket 4bbl. dome that i dont know where to get yet? prob. jegs or summitt racing so is the 305 vortec heads ok? or the 350's???...i got a lead on some 305's for 170.oo$$bucks complete as well. so whatever anyone can tell me would be just great, oh yeah i'm going with flat top pistons as well and a 2500 stall converter too, possibly roller rockers!!?

THANKS,IRONBOSS.  
IT'S NEVER DEAD TIL' IT'S CRUSHED..!!!

350 vortec heads are better but when using flattop pistons your compression will be high. Dished pistons and 350vortec heads would be more streetable  

+1.I have the aluminum vortecs and love em.  

the vortec heads have a different intake bolt pattern also.

if you are able to mock these heads up ,the 350 heads have 64 cc chambers so u can get good compression out of them. im not too sure on the 305 vortec head stats.

if you buy the heads bare , you can install beehive springs on them , they are really good springs and there is no fabrication needed to install them. another good idea would be to get 2.02 valve heads since u have some cubes.

spring upgrade is required if installing cam with over 450 lift.  

http://www.chevyhiperformance.com/tech/engines_drivetrain/cams_heads_valvetrain/0606ch_cylinder_head_performance_test/index.html

here are a few vortec head comparisons.  

Blacksheep is right, cam lift is very limited by stock springs on vortecs. After market vortec heads will have better springs but you  need to make sure they will work with the cam  

so what kinda compression am i lookin' at then w/ 350 vortec heads an flatops? what kinda troble will there be then?? detenation,pinging??ruff idling??.
what kind dished pistons can be reccomended? and can i just put the 2.02's valves in or does it need gringing for fitment from a nearest engine shop as well? got a cam size for me? or just tell the engine shop?
thanks for the quick replys.
IRONBOSS.  
IT'S NEVER DEAD TIL' IT'S CRUSHED..!!!

so the intake bolt pattern is different!!?? so they CAN'T bolt on to my 400ci.at all!???ok,ok.. yah so i need vortec compatible intake right!?..at jegs or summitt?and do they have carb intakes for this application?
thanks

IRONBOSS.  
IT'S NEVER DEAD TIL' IT'S CRUSHED..!!!

they will bolt up to the block you just need the vortec style intake.my aluminum vortecs are set up for both kinds of intakes  

I just put the vortec heads on a 350, used the beehive springs and an Edelbrock Vortec intake. no problem! Obvious power felt too as a result.  

Seats will need to be cut for oversize valves[2.020]. He's gonna have high compresion putting them on a flattop 400 engine. Unless your running racefuel you need a dished piston. The cam depends on what your looking to get out of the engine.  

the 350 heads would be optimal, and if u want to upgrade heads in the future you should not have too much trouble finding yourself a buyer for the vortecs.

the vortecs heart shape helps vs detonation.