Finding any good 305 pistons will probably be a challenge. Not many people build 305's.
I'd probably stroke it to a 331 and then boost it. I did play with a 305 once a while back. I also entered a bunch of info into comp cams camquest software (like desktop dyno), entering crazy stuff like 30psi boost with a big turbo (just picked one out of the list) and entered whatever valve sizes and all required info..
Came up with like 900hp lol But the mods to get that would be expensive.