i very well could be wrong about this, but i think i remember smb telling me that they will do pop tops on the chevy/gm 1500 awd but not much else inside, etc becuase of the wieght.
i too came from a syncro westy and was also looking at the chevy awd... in the end i found the e350 quigley eb50 to be so much better than the westy, but im sure i sucks a lot more fuel than the chevy 1500....
i think that for snowy roads, limited fire roads, etc the 1500 awd would be great if you only want to do a partial build.
have fun,