[jonzcustomshop]

so the good news is that the rust did not get into the lcf only part of the footwell.
you have a little fabrication ahead of you, but I still think you will benefit from front and side floor pans and outer rockers, the main difference in the lcf cab is where the footwell is modified for the tire clearance.
you do not need to buy inner rockers, because they are part of the front and side floor pans when you buy them.
also, good plan leaving as much original metal as you can, I suggest trim out what is bad, and use the patchpanels to fix, you might run into a small bit of fabrication if the rust got into the foot well , but it is not going to be any more work than your initial repair.

* super important on this kind of repair, as you cut out pieces of the rusty metal , save it all till you are done, you might need parts for patterns, and if the very front of the rocker panel is different than a c/10, you might need to cut and splice some of your old pieces.
btw, cool truck, what engine does it have?