I did mine right on the frame,I put a piece of plywood down and just gently rolled it onto a block and lightly secured it with a strap so it wouldn't get knocked off.The cab is pretty solid and it doesn't weigh much empty.Probably not the best way but it worked good for me with my limited space and resources. cab pic
The firewall is a lot stronger than the back. Just make sure you cushion it with some wood and brace the door frame if you are going to weld in new metal so it doesn't go out of shape.
Paint & Body Shop moderator A lone amateur built the Ark. A large group of professionals built the Titanic.
Yeah a wood brace in the door is a good idea,just to be safe. Drew,that little machine is the handiest thing I own,engine hoist,garden tiller, dog scratcher ,and sometimes I even use it for work It's a real backsaver