230 & 250 CI engines have the same size bore BTW.
I believe you can install a 250 crank into your 230 block & order 307 or 250 pistons.
That will make it a 250.
If you are going to get stock stanadard compression pistons,you can install a 194 (small chamber) cylinder head to raise the compression a bit.
MBHD
Last edited by Mean buzzen half dozen A.K.A. Hank; 04/18/08 09:14 PM.