a 350 has a 4.00" bore in it-if you try to get a 4" bore out of a 307 ur gonna have no cylinder walls and need sleeves and spend alot of time and $$ doin this-not to mention gettin the deck back to square and flat-not to bad to have done with one sleeve but all 8?-save yourself time and a few gs-just find a 350 or roll ur 307
sounds like it needs sleeves either way-really up to u but id just get a 350-save time and alot of machine shop $$-that shits never cheap-but if you want sleeves and got the extra cash i guess its up to u-but its really only gonna be a 307 with 350 pistons-stroke and everything is a lil different-would need new crank and some more shit-id just get another motor-like i said save time n $$-why do things the hard way? :biggrin:
They can't bore a 307, because they won't be able to find .030 over 307 pistons. 307 pistons are 283 pistons with a different wristpin height.
They can't turn a 307 into a 350 or a 305. There is a chance they can bore it to 4" (like a 350), which would effectively make it a 327. But even that's doubtful, there's only a few 3.875 (283/307) casting #'s that have jackets thick enough to take it to 4 inch.
A 307 is a 283 block with a 327 crank, basically a stroked 283, so i don't understand why people hate them so much. The other way around, a de-stroked 327, a 327 block with a 283 crank, is a 302 zapper, and they're regarded as one of the best chevy smallblocks ever made, when people hate on 307's. I don't know why, I think people are just dumb.
if you want a 350, go buy a 350. If you want to keep your OG engine, see if the machine shop can bore it to 4", sounds like they can, but that's a 327, not a 350.
If you do end up going and buying a new 350, your crank out of your 307's worth at least 100 bucks to someone, put it up for sale a a 327 crank. Same journal size, sane throw, same balance, same crank.