Don't limit your search to 250's. The pan from a 194, 230, or 292 should also fit. Finding a new pan probably isn't an option, but there should be plenty of used ones available. Try contacting a rebuilder such as Jasper or one of the other engine rehab businesses to see if they have an extra pan on hand. I can't imagine that there's enough demand for those engines that they would refuse to sell you a pan off one of their "core" engines.
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!