1973 340 issues.

Every word. You didn't explain anything in depth. The leakdown test is not really for diagnostic purposes like he needs. It is more of a tool to measure the percentage of wear on certain items. He will have much greater success simply pressurizing the bad cylinder with air.

A leakdown test certainly has its place. He has a cylinder though that would probably not even make a leakdown test register, so for him, it is a waste of time.
Actually i did, you are not smart enough to listen. it would be the air escaping that would tell him where his problem is.