Deciding on a 4-speed Transmission

[argonaut]

I'm trying to decide which transmission will go back into my 66 when I re-install the drivetrain. I have two sm420's available and an sm465. The motor is a bbc 402 and I'll be using a divorced T221 rockwell transfer case.

Any reason why I should use one vs the other?

The truck will be mainly used on the street with some off road use on weekends, but no crazy wheeling over boulders and up shear cliff faces...