That's need to know info. What I would do would be go for the 4 speed OD......unless he's just DYING for an auto. For about twice the cost of what he was going to spend on an incomplete adapter kit he could probably get one made for a 4L60E GM transmission. That's what I would do.
4spd overdrive, that’s genius. Weight of truck wouldn’t be an issue on 4spd OD? It’s not like slant 6 is putting out loads of torque. May of answered my own question there.