Rear end gear size?

Hey66Cuda,
Read YOUR POST #6You state that you are going to "WORK ON" the rear end latter. What does that mean? Change gear?
Well who ever sells you the converter will have a lot more questions than WHAT GEAR WAS IN THE CAR WHEN YOU GOT IT.
They will want motor specs, including cam, compression, maybe even intake manifold type, tire size, weight of car, and yes the rear end ratio.
That stuff sounds like it will be addressed "EVENTUALLY".
Put your mind on the converter then, not today.