Which Transmission????

[REDSOX04]

I have a 65 short bed step side that I'm rebuilding, its in about 9,567 pieces right now. I have the Straight six 230 that I'll eventually rebuild. My rear-end has 3.73 GR in it. My question is.. I have access to a 55 power glide for free, I also can get a TH-400 for $50, both would have to be rebuilt. Then I have a 700R4 that I rebuilt a couple of years ago while in school that I'd rather keep for a 350 I've got for a future project. I'm torn on what's the best choice. I'm still relatively new to the restoration world. I was a helicopter mechanic for 10 yrs, Military and civilian, then went to school for welding and automotive. This is my first project and thought I'd see what you all thought. Any incite would be greatly appreciated.