[tprunier6]

Yes it pulls above 7000 and I play at higher rpm's on hard acceleration. Probably 9 to 9500 momentarily. In lower gears rev's build fast as you are finding out so getting a sense of where the engine is producing usable power depends more on the rider than watching the tach ... which given it's age and construction is accuracy challenged.
If you are pushing the engine make sure the carbs aren't leaning out, keep the oil full, fresh and make sure it is flowing. There is a good pump modification that ensures more flow, do a search in the 350 engine section or look elsewhere on the web, oil pressure in the 350 engine is measured in ounces and the top end is splash lubricated as is the rest of the engine. Personally my choice of oils is 5-40 full synthetic Rotella.
You should also look into making a keeper for the push rod seal as it will push out from crankcase pressure and dump the oil faster than you will realize. View attachment 318553

This damaged piston picture seams linked more an Ignition advance problem (too many advance !) than oil problem , who will kill moving parts in your cylinder head more certainly. no?