The 250 piston has about a 1/4" deep dish across most of the top of the piston. The 230 has four shallow valve reliefs, since it's the same piston Chevy used on the 283 V8 engine. With a bright flashlight and a long screwdriver, it's pretty simple to tell the difference in the piston shape.
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!