I have a stock 350. I am looking at cams and found Comp Cams 08-601-8K - Comp Cams ZZ4 Valve Train Power Package Kits on the jegs web page. Was wondering if I would half to change anything else out, or should I be able to drop this in and be ok. It says adds 64hp. Looking for advice.  

The cam's performance gains are subject to other factors. The ability of the cylinder heads to utilize the additional flow is probably the biggest.  

'Canted' makes a good point. How about the exhaust system. If you throw more exhaust gas into a "backed-up" system (backpressure) it will increase exhaust gas reversion and pumping losses at the high end.  

I just instaled headers with 3inch collectors and twin turbo muflers. The largest pipes they told me would fit on my nova was 2 1/2 inch. I ordered a kit from Jegs. What else do u need to know to help me decied what to put in the engine.  

which stock heads are they 64cc or 76cc this is a factor in deciding the cam also if they are big cc then go with a 1000 to 5500 cam and make great torque, but if they are higher then you might need to make other changes with a cam swap just some things to look at not just how many horsys you will get.

Fattys Chassis and Speed Parts  

The ZZ4 has a 10.1 comp. ratio to make use of this cam. I didnt look at the Comp specs. but should'nt be very different than GM. Your stock 350 probably has 8.0,8.5-1 comp. ratio. An engine that already suffers from low compression doesnt need to suffer further with a late intake closing point. That will kill torque, as compression makes torque. Look for a cam with an IN. closing point of 60-65deg. ABDC to make use of 8.0,8.5-1 comp. ratio. That will make torque and that gets it done on the street. Dont ever count on a camshaft alone to deliver 64 additional horsepower. Like those other guys said, camshaft power gains depend on a slew of other factors. Almost any time a cam change makes more power, it puts peak torque at a higher RPM range.  

Here's some positive things working for you or another way to look at it...

The ZZ4 mid-80's aluminum vette heads flow poorly...so if you have a 882 head or something similar they aren't great either.

To bump compression a little bit, maybe get you around 9:1, if you are willing you could pull the heads and put a Fel-Pro .015 steel head gasket on- would also help your quench.