I went with an auto as I did not much care for the NV4500. It is a bombproof tranny but they shift horribly. As the 80 is my wife's DD now, she decided to go with an auto. Much nicer driving now compared to the NV4500.
I went with a heavy duty built 700R4 and a heavy duty 700R4 diesel torque converter. It shifts quite smoothly. Although, I still don't have the lockup hooked up yet. Someday, I'll get to it.
BTW, with my heavy 80 turing 35's and no lockup, I am getting 20-21 mpg. Not too bad.
What are the specs of the 700r4 & TC?