The plan was to change out the floor under the rear seat as it was shot, change 1 inner rocker panel and fix the huge shifter hole in the floor. After closer inspection, the floor was replaced, but brazed and riveted in, the crossmembers were rusted out already and both inners and outer rockers were gone. So now I'm going to replace floor with a 1 piece with inners attached, and replace the outer rockers. Also, the front body mounts are gone, and the firewall has been hacked up at steering wheel opening, not to mention the hammer fit they did for an HEI distributer. I've decided to just change the firewall also. 

I started by cutting the floor from the outer rocker and removed the rocker itself. Actually 2 outer rockers on each side, I was able to rip the replacement off by hand on the drivers side, and cut out the original spot welds for the original rocker that was half there. The cowl area where the rocker attaches is pretty rusted out so I'll have to patch that up.

The new drivers rocker panel fit really well. After I checked it with the door on, I spot welded it in place. Exact same with passenger side, I now have both in with the old floor still in place, just not attached to rockers. Car is on the frame the whole time.
The first picture shows the body lifted off the frame.
Second picture is of the drivers body mount and the rust that goes with it. Actually all the mounting areas on the body are shot. I'm going to change the firewall first and use those 2 mounts as reference for the floor and then the trunk floor.
Third picture is drivers rocker(s)
4th shows new rocker in place and area I had to cut out that was rusted through.

I patched up the lower cowl areas on both sides with some thick sheetmetal, and coated everything in POR15. Firewall was pretty straight forward, welded it in then clamped on the new body mounts. The firewall came with 2 drivers side mounts. I had previously bought 2 mounts because I thought I was just changing those  and not the firewall. I'll use those, they have caged nuts on them anyway, while the others don't have any. Before welding them on, I lowered body onto frame to make sure all the other mounts ( what's left of them) lined up to the frame. Also, I think the cutout for the wiper motor is backwards, the right bolt hole is covered while the left side seems to go farther than needed. I'll just drill out the covered hole, and seal any gaps around the cutout.

My frame was already restored at some point and still looked great, with the body up, I painted it with POR15 and I reinforced the rear lower control arm mounting points. I just welded a piece across the top and added a gusset in the front. Next, I epoxy primed the underside of the floor and painted it with Eastwood Chassis black. Pictures not that good, but it turned out really well. I painted all the way back to the rear seat area, after I change the trunk floor, I'll lift up the back of the body and get the rear half the same way. I don't have a rotisserie, and didn't want to make one I'd only use once. The engine hoist works great, I just don't go underneath, I was able to get it high enough I could reach everything from the outside.