The 94 heads would be what you want to run. The 64 are too big chamberwise. Compression would be to low.
My 64 has the same 350 in it you are talking about. It is a 71 350 with 94 heads.Runs OK. Has 2 barrel is probably stock.
I have a 389 that I have been trying to finish, and will this winter.
Pontiac engines are out there. Just need to look in the right place. I know where there is a 68 400 4bbl, and a 73 400 4bbl both good cores from a reputable guy.
The carb you have will be too big if it is a 750. A 600 would be closer to optimum. A quadrajet on a stock pontiac 4 barrel intake is a great combo...believe it or not.
one of the comp cams XE grinds might be a good cam choice. Maybe a Lunati VooDoo. Nothing wrong with a summit cam either.
Something like a 212/218 @.050 would be plenty for a 350.Dont go too big, especially on a 350.
Fact is stranger than Fiction