Why wouldn't you use the NP435? It's a rat rod. The 435 is perfect for that type thing. It's big, brutal and indestructible. I am actually on the lookout for one for my rat truck. I would swap my 833 OD straight across the board for a good NP435.
The only "drawback" is you cannot speed shift with one......but you'd be surprised how fast I can shift one. I have Borg Warner's version in my Ford truck. The T18. It's still in good shape and shifts really well. Kitty even drives it all the time and likes it.
One thing's for sure. The NP435 won't break.