Today I brought the disassembled block and parts to the machine shop. They're going to bake it clean, shot peen it, then bore & hone the block and prep it for rebuild for me. I don't have any of the right tools or experience for installing cam bearings so they'll do that too. They said they'd look in their inventory for some different period correct (HAMB friendly) heads with larger valves and get back to me. The connecting rods will be resized and the crank will be ground & polished too.
When I got back to the shop I took the doors off, yanked the seat and then the gas tank, and vacuumed the crud off of the floor, including several rodent nests.
There was a bit of rust underneath the trim piece at the bottom of the door on the driver side.
With the seat gone, I vacuumed up the rust flakes from the threshold. You can see that it's not really that bad, but the vertical piece of steel that goes under the threshold trim piece is completely rotten:
No more fuel tank.
