[Rick]

The underside of the piston would also tell a story if it was lean and got hot at one time. Based upon the jetting specifications that would be close.

I would clean the power valves. As for the jug I'd run a scotch bright pad and WD40 to remove and shiny spots that could be aluminum deposites.

Measure ring end gap and go from there. Makes sure your using the same base gasket thickness as before.

In your picture the ring end is not alligned with the piston ring pin....don't over look that, or there will be an issue.

You mentioned that the plug was white....lean......make sure you don't have an air leak, reed block baskets, main bearing seal (ignition side) or cracked carb boot. I'd run a BR8ES once i got it back together.

Motul 710 is a great oil, burns cleaner than the 800, however for long deep sand washes at WFO i think I'd step up to the 800 and try a 50/50 mix of race gas and 92 octane, there may have been some detenation (pinging) that went UN noticed. Those long hard runs can really heat up a motor, so a main jet increase must do the trick as well.

Food for thought.......

One other area to check, water pump impeller....make sure it's not deformed or melted. Now's the time . Do a search.....plenty of info on that subject.