Three on the tree options

Go with the 230, and don't look back.
I think the 230 is a floor shift only tranny, but in my experience, it is a good tranny and it was available on the 383 magnum in 1970 B-Bodies, so it has to be strong.
If it's good enough for a 340 in A-Bodies or a 383 magnum in B-Bodies, Chrysler had to be confident in their strength...