Would the body mounts of the '90 be the same width as the '83 frame rails? That would make it a lot easier.
I was thinking attach them to the body, then drop that onto the frame. Then just adjust height of each mount to sit level. Make the frame side connections for the mounts in the location of the '90s
Better than putting the '83 mounts on the frame and then modding the body to fit that configuration right?