What about the BIG nut on the bottom of the down tube? There’s a plain nut on the front and the water tube fitting at the rear acts as a nut to. The pinch bolt is out so it should come apart as there is only a tab at the top of the driveshaft connecting it to the crankshaft. No rusty splines to deal with on these ones!
Right above the pinion gear is the 39-65 collar which has to be pried up so you can drive the 18-84 pin out. Once it is out, the pinion shaft should come out of the housing leaving the pinion behind.
I can’t find any good photos of one disassembled but I can always go over and take a look at a couple of gearcases I have in storage.
