[climb any hill]

That's alot of carbon buildup on the piston but not bad. You might of been running rich but then lean when the reed broke and sucked more air in.
And that's prob why that plug doesn't show fouled. Get that new top end kit from RJATV.
Also on that head hasket, it's not fully open on all the water jackets. Not sure sure how much it will effect your coolant routing???
Is that the correct gasket or is that how they're made for R's?

Sell that Blaster Hot Rod Crank & Engine gaskets.. make money for R parts!!