Well I cracked open the crankcase, and the good news is that the crank looks fine under the upper and lower bearings.
The pitting under the upper seal is significant. My son has the facilities at school to turn the crank, can I machine this section down, or sleeve it?
I pulled the pistons (after marking the rods), and the one is pretty chewed up, so I’ll be putting new ones in.
I did get the carb rebuilt with a new float and seals.