Oh I see. I thought you meant you already had a 500hp Buick 350... Yeah I would think building a Buick 350 would cost a fortune! You can build a 400hp 350 SBC for pretty cheap with junkyard Vortec iron heads. The heads is where everything gets expensive. With a Buick 350, what would the best cylinder heads be that aren't aftermarket? There never really was a "high performance" Buick 350 was there? So would the pre-smog heads be the best?
I
guess the pre smog heads were better, but the 350 was a smog era engine. It was made from 68-80, and really only had a single year of good performance in the 70 GS Skylarks. 315hp, 400torque. There are really 3 types of factory iron heads, the 68 and 69 heads that oiled through the rocker shafts and will NOT interchange with 70-80 engines without serious mods (the blocks as well), the early 70s non smog era heads, and the early-mid 70s to 80 smog heads. In 1979 they had slightly larger exhaust valves. They are a well designed head on paper, but in practice they are lacking in stock form. Porting on the exhaust side helps them out a lot. All of them had anywhere from 50-58cc chambers. Large open chamber design, no quench area to speak of. Buick changed compression with pistons rather than designing a whole new head, a good move IMO. All things the same, take an 8:1 motor (closer to around 7.8) and swap in "10:1" pistons with the 10cc dish rather than the ~24, and you'll be around 9:1. TA has new closed chamber (heart shaped) heads in the works, but they are north of 2k. But they are a serious leg up on even maxed out iron heads, plus they are a bolt on thing. Can even use factory shaft rocker setup and valve covers. To
actually answer your question, the best heads are whatever you can get your hands on. They are all the same for the most part, aside form the 68-69s as I mentioned. Aside from water passage differences between the 70-73/4 engines and the 75-80 engines, I think those heads are the same. Flow and valve wise, no real discernible difference.
