Run- - - -do not walk away from anyone who thinks 235 and 250 parts will interchange. Maybe he meant to say 230 and 250? They use the same block and cylinder head, with different crankshafts and pistons. If the engine is a 250, you can use pistons for a Chevy 307 V8 to get a little more compression. The 250 piston has a dished top and the 307 has all the same dimensions with a flat top.
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!