Started on the top end today. Measured up the ring end-gap and then looked for some specs for the TKRJ brand pistons, but couldn't find anything. So I looked at the Haynes manual, the Clymer manual, the Weisco and Pro-X websites and realized they are all different. Given these don't seem overly tight or loose, I started the assembly.
Pistons and rings
Got as far as trying to install the small-end bearings. Seems like there is a bit of difference between the different manufactures when it comes to bearing length.
Top bearing is the Pro-X bearing I got with the crank re-build, which wouldn't fit in the pistons I ordered. Bottom bearing it what was in the engine.
Gave a call to HVC Cycle, where I bought the pistons and they said the OEM will fit. Ordered them along with the points cam I needed. Should have all of it in two weeks. Until then I'm off to find new screws for the stator-side and a new brush or two.