If I remember correctly, the transmission you have is a floor shifted non-synchro 3-speed. Something that looks similar but has synchros would be my choice.
But if you're replacing the transmission and rear axle maybe a swap to an automatic would simplify things enough to make that the right approach. You eliminate the clutch linkage that way and there are after-market automatic shifters that look a bit like the original 3-speed shifter.
If you are going automatic then looking at the 230/250 motors begins to make more sense. It won't look as original under the the hood, but you don't have to deal with adapters to put an automatic behind one either.
