Body Mount Repair

I just got a 93 Jimmy from a friend. The main problem with it is that the 2 front body mounts just behind the front wheels are rusted out. The driver side it is actually pushing up into the cab. The sheet metal on the floor is cracked all around the body mount point and on the floor is a bulge above the body mount in the cab. I was wondering what would be the best way to fix this myself or is it easier and more expensive to take to a body shop for repair. Any help is appreciated. I don't mind doing the work myself. Just would like to do it right the first time and not have to do it twice as it is a fairly big problem.

I have had 2 of these trucks that it happened to. I never did repair it. What I did was jack the cab up and stick 2x4's between the cab and the frame. This was suppose to be temporary. I thought about getting some sheet metal and pounding out a new cab mount and welding it on. I think this job would be better suited for a body shop because they have the proper tools. I wish someone made a repair part for this problem.