I'm running the ZF trans that was originally behind a 460. It seems to be a pretty good tranny, same problem as the nv4500, gear split between 3rd and 4th is too wide. If I were offered the 4500 or the zf side by side for the same price I would probably go with the 4500. It seems to have a little more solid feel to it. However, the zf is cheaper. I only gave $250 for my trans and 1356 x-case. Hard to get nv4500 for that. I have every confidence that it will handle anything me and my 4bta can throw at it.

Also this trans was originally external slave cyl. I cut all that off and used the ford manual clutch linkage. Some minor mods but it works well
Carl
1979 F-250 crew cab 4 x 4
4 bta with modified H1C
Cold air intake
ZF S-42 5 speed
Borg Warner 1356 x-case
Dana 60 rear
Dana 44 front
3.55 gears
255/85R16 tires (33.5x10.5)
Hydroboost steering and brakes
Custom 40 gal. fuel tank
Much more later