Well, since you asked
If you're not going to put it bak like factory, no reason to consider a 4spd granny tranny...they're pain to drive daily.
But if you're on a budget, and the engine runs well in the truck now, then go for it, other wise a 350/TH350 swap is cheap and easy, a 350/700R4 (AOD tranny) is a little bit more, either are very much improved over the truck transmission.
You mentioned in your PM to me yo didn't have a grille for it, or you just didn't have it on? I have a '57 Grill and a few 55/6 grilles too, depending on what your plans are.