Well, any time you change engines there is always something you run into that you haven't figured on. I put a 396 in a 350 hole and it wasn't bad, but it did require some changes, mostly in the area of the cooling system.
I would look for a good 235. There have to be some out there. If you can't find one, the 250 probably wouldn't be that difficult. I know you would have to fabricate engine mounts, get a new bellhousing and somehow get your radiator hooked up to the engine. Also, I don't know if you could use the original generator on your engine or have to adapt the vehicle over to an alternator. If so, that would be considerably more time and probably money, depending on how much stuff you have on hand.
