Dont forget to have them also do a compression & leak down test to see what that shows.

A wrist pin can make trhe noise you describe but pistons can alsao run many miles/yrs with a cracked skirt too and wiil make noise/knock sound that can sound somewhat like a worn wrist pin too.

Still could be a bad lifter because the top end will make nose with a colapsed lifter due to clearance at top of pushrod in head at rocker arm and lower portion of motor where lifters are house will still be relatively quiet for that reaosn.

Coiuld also be worn rocker assembly or bent pushrod fro prior owner overreving it it he somehow disabled the stock 4,500rpm rev limiter.

It will be inetresing to see wha it turns out to be becasue iunfortuantely on the intrnet we can hear/exprience the noise you bike is making which make it harder to try to diagnose it from a laptop screen unless maybe you posted live video of the noise if it could be heard well enough .

Good luck.

Scott