I would only do six shooters if you are using ram assist or just a ram. Otherwise 60 knuckles will be pretty strong. You just need to keep the trunion nuts tight. They are basically something that should be tightened before every trail.
There a small bolt pattern and I'm putting the gm box on it just waiting to put a motor in it to see if it needs a cut and turn for the soa. Just looking at options for stronger upgrade if it needs it and I will do a high steer on it with the soa
It's a disc axle already from a 76 just trying to see if there are w weak links to get rid of I'm rebuilding the whole 40 from ground not much will be stock but the frame and body since it's a 64 and parts were hard to find so I've been selling mine and modifying as I go to make a nice 40 that fits what I want to do