A500 42RH transmission in Arizona

My intent is to use it behind a 5.9 Magnum in a 1941 Plymouth. If I get a used one, I will get it rebuilt for my specification/need. As for the lock up or non lock up, I want to have the option of overriding the hydraulic setup via toggle buttons for the lock up and for the overdrive.

The car is going to be a street driven, so my goal is to make it both strong enough for use behind the 5.9 and handle spirited driving if it ever occurs.