I feel your pain in making this decision. I'm a slave to originality, and I'd want the early 235 back in my truck. Do want, in fact - the original engine in my fire truck was probably (don't know for sure, missing serial #) the early 235. Had a 216 in it, which we rebuilt from head to toe. Aluminum pistons, insert bearings, hardened valve seats. Runs great, though it still struggles to pull the over-heavy fire truck.
Right when you said "working truck" was when I switched to thinking you should get the later 235. It's just a better engine - more suitable for the work you're doing, with the pressure oiling, higher rev. limit, etc.
If your gut is stuck on the original engine, allow me this one thought: why not get the crank welded up and turned, and rebuild the original 235?
Plenty of options for you, none of them bad, really. I hate to part out one truck for another if it's not necessary.
My $.02 anyway . . .
-Michael
