There would be no problem building your spare engine as a 250- - - -just do a crankshaft swap. If the 230 crank needs top be reground, the cost would be virtually the same, since a reground 230 or 250 shaft would be almost the same price, and they will use exactly the same bearings.
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!