This evening I finished the access hole in the left gear tower by filing/sanding it to size. Next up will be drilling the holes out to full size for the screws, and installing the nutplates. (Tomorrow, maybe.)
Speaking of nutplates, I installed about 40 of them in the floor support angles. Only about 75 to go! There were several places where I used one-lug nuts because of the underlying structure, and a couple of other places where I'm still scratching my head about how I'll make it all work, but overall, I'm pleased with this whole floorboard project. I figure it'll take me about 30-35 hours of total effort to split the floorboards into multiple pieces and attach them entirely with screws and nutplates. Not a bad tradeoff for the great utility I'll get out of it.