The short block of the 292 will be the same no matter what year you choose, the head changes to the integral type somewhere in the mix. If you go with an older head with separate intake and exhaust manifolds, pick the engine with the least amount of wear and tear. Grab the HEI, and wire harness for it.
Moving the radiator does two things, gives room for fan and water pump, plus lets you lower the radiator so the fan covers more of the core. The water may set a little lower on the 292 then the original engine, the 250 sure does. If the exhaust manifolds come off the head, measure the outlets and grab the largest one, some if not all 292's use bigger outlets then the 230/250 did.
