Also with the sheet metal parts, I received a heavy-duty Blair spot weld cutter. It works like the economy spot weld cutters but has a much more aggressive, and stronger, cutting blade and chews through the spot welds with a lot less effort.
This new cutter gave me the motivation to start tearing through the welds that attach the inner rocker to the outer rocker and I made some progress in just a few hours. I left the lower seat reinforcement in place so I could use it to fit the new rear floor support rail and the front floor support patch.
I needed to make the patch first because I had cut the old rusted floor support due to the fact that it looked like swiss cheese. So, I painstakenly, surgically removed the badly damaged bottom portion of the front floor support from the badly damaged front floor support rail and straightened it up to use as a template for cutting the new patch out of the new front floor frame patch metal I had just received from NPD.
I have recently purchased some disc brake assemblys scavanged from a 1971 Ford Ranchero and thus needed to get a sand blasting cabinet to clean them and the various other rusty parts from this Mustang. The above hunk of rusty metal was the initiation test for the new blasting cabinet. Using the medium sized nozzle for the included blasting gun, the load didn't seem to tax my smallish air compressor too much. I could blast for about 30 seconds continuously before the compressor would need to restart and then continue for quite a while longer while it ran. I think it'll work fine although it may work better with a so-called pressure pot blaster. I think for the above test, I should have used an aluminum oxide media rather than glass beads as the glass beads did take off some rust but really just shined up the part.
Aaaaanyhoo, after cutting out the new patch, I test fitted it and the rear floor support against the lower seat reinforcement pan and the tunnel cross member. You can see the new patch tucked into the floor support rail where it's supposed to reside. Next I need to tack it in place, remove the rear floor support and then weld everything back in. Only then can I cut away the old lower reinforcement and finish removing the old inner rocker.