You'll need to have some pretty high compression or turn some high RPM to get 350 to the wheels on motor alone, but that's not to say it isn't doable. Your average set of TW's or AFR 165's, GT40's, etc. aren't gonna get you there though. It's going to take a considerable amount of port work + shaved heads to bump compression to 10.5:1 ish. If you have a valvetrain that could withstand some RPM, you'd have a better chance of reaching your 350 HP goal than if you were trying to sneak in under the factory 6250 rev limiter. I'm talking in the 7-7200 RPM range. You'll probably have a car that isn't very fun on the street though because all of your power is going to be on the top end where you never use it. If you were willing to shoot for a lower number or add some boost to the equation, you could very easily reach the numbers you're looking for and still have a car that's streetable. 400 wouldn't be unheard of without the nitrous with boost.
I think you could make 350 rwhp, but it ain't cheap or easy with a 302. Get the right cam (high rpm solid would be best) in there and spin the hell out of the motor and you might be able to pull it off with the stock shortblock and box-stock heads. You'd still probably need to port the lower intake.
A more streetable way to do it would be port the heads or get AFR185s, stroke that motor, and put in some high comp pistons. If I did that, I'd be looking for over 400 to the wheels.
You'll need to have some pretty high compression or turn some high RPM to get 350 to the wheels on motor alone, but that's not to say it isn't doable. Your average set of TW's or AFR 165's, GT40's, etc. aren't gonna get you there though. It's going to take a considerable amount of port work + shaved heads to bump compression to 10.5:1 ish. If you have a valvetrain that could withstand some RPM, you'd have a better chance of reaching your 350 HP goal than if you were trying to sneak in under the factory 6250 rev limiter. I'm talking in the 7-7200 RPM range. You'll probably have a car that isn't very fun on the street though because all of your power is going to be on the top end where you never use it. If you were willing to shoot for a lower number or add some boost to the equation, you could very easily reach the numbers you're looking for and still have a car that's streetable. 400 wouldn't be unheard of without the nitrous with boost.
I've seen an AFR/FTI/Performer intake combo that made 340 to the wheels at less than the stock limiter. I think it could be done with GT40Xs, but like you said it will take rpm, and the right cam.
Yeah I'd get different heads if you can. GT40's are okay but AFR 185's or TFS Twisted Wedges are better and emissions legal, if that's what you're after. I'd look at the Comp Cams XE series of cams.
The easiest way to do this would be using a 331 or 347 with about 10 to 1 compression and a set of AFR 185's. You don't have to have the extra cubes to do it though. It could be done with a 302 but it would have to be a well thought out combo like 5 spd GT suggested.
If money wan't a object and I wanted to do this with only a 302 I would probably go with a 10.5 to 1 compression 306 with CNC'ed TFS 185cc twisted wedges, holley systemax intake, FTI custom cam, 70mm accufab TB, lightning maf, 30lb injectors, AFM N/A power pipe, 1 5/8's long tube headers, and a good tune. With the rev limit moved up to 7,200 this combo I think would easily crest 350hp and would love nitrous. I would build this off of a early model block with conversion hyd roller lifters for block safety. roller blocks don't like rpm's.
Get the cam ground for everything specific you will have - exhaust primary size needs to be known as well...it isn't as simple as saying run this or that exhaust.
Get ready to lose an accessory or two and some vacuum at idle...
Get ready to spend some money...
Get ready to approach 6,500-7,000 rpm...where peak is made isn't the issue but the power you make before and after