The only difference in a 230 and a 250 engine is the length of the stroke- - - -they use the same block casting and the bore size is 3 7/8" on both engines.. If you can get a borescope into one of the spark plug holes, look at the top of the piston. The 230 has a flat top piston, and the 250 has about a 1/4" deep dish in the piston crown. You might even be able to check the piston with a long, narrow screwdriver blade with the piston near the top of its stroke.
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!