Hi,
could someone please clarify for me if i can use these on a chevy 250 without having a compression change? Any other problems? What about the 307 pistons? Thanks

Drew The 230's can use the 283 pistons. and the 250's can use the 307s hope this helps }[oooooo]

ok thanks. but does the 307's affect the compression any and if so how much?

Yes it will depending on a few things 1) if it has the valve releafs in it and how many.2) how much the head has been shaved/milled.Or angle milled. 3) if the block has been cut to a zero deck. it can very from about 9.5-1 to as much as
10-1 Plus. So i can't tell you 100% Because I'm not the one building it. but i hope this helps
}[oooooo]