The fact that you have silver sludge in the crankcase is proof of piston skirt wear.That is caused by piston skirt rubbing the cylinder wall. Usually most noticeable under heavy load. Whether and under what conditions you hear it may vary. Poor timing by itself does not cause that kind of wear but a loose piston in an oval cylinder will suffer from poor timing more dramatically.
You started off this thread with "PO put new piston and rings in..." Now you are about to repeat his mistake.
What's the definition of insanity? Doing the same thing repeatedly and expecting a different outcome...
Not saying you are insane, don't take offense. Just sayin' you're in denial.
All that being said, if I were not building the machine for long term work, maybe just tooling around with a cart or something, that didn't stress the engine, you might be able to run it for a number of years with just a ring job. But to cut grass, plow, snowblow, think about the time you'll have invested and the long term payback of a fresh engine. We've all made the mistake you are contemplating.
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