I have been thinking about this and now I have some doubts about the cross members. Many years ago I put a 235 chevrolet engine in a 53 GMC suburban. I welded an engine mount to the original GMC cross member. Later I changed the cross member with a chevrolet cross member and bolted the GMC radiator frame to it. I don't remember any problems doing that, so if you are going to bolt chevy sheet metal to the GMC frame, unless you are going to install a 235. I think you can do this without changing the cross members. Just take some measurements. Sorry for the confusion, but then thanks for rattling the gray cells!
