The difference in the 230 and the 250 is the stroke. You would need to use a different crankshaft and turn it into a 250. The 230 has a 3.25" stroke; the 250 has a 3.531" stroke. The 307 piston would stop about 1/4" short of the top of the block, and the compression would be about 6:1. Performance would be a bit below par!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!