Leakdown / compression test

(Disclaimer - forgive my ignorance, motors and anything electrical is like learning Chinese for me)

Hey guys, I have 170K motor that is still running strong but I'd like to think I could dive into rebuilding... or just order a turnkey from Rick I have looked at several informative videos on how to do theses test. My question: Leak down - does it matter which cylinder I test as long as it's at TDC? I've learned that 10% loss of pressure is acceptable... true? (Im cautiously optimistic, I know my motor is tired). Compression what kind of numbers should I be seeing, whats an acceptable percentage difference in cylinders.

Thanks guys, I will likely yank and scrap the motor and just purchase a turn-key, but if nothing else Im going to tear down my existing motor for the experience.

Adam