The decompresser on the camshaft bumps the exhaust valve when the starter is rotating the engine, once it fires off, due to centrifugal force, the bump on the decompresser that opens the valve slings away from the cam lobe and stays out of the way. it's possible that it might be a issue, but not likely.
a leak down tester pumps air into the cylinder via the spark plug hole. Piston at TDC, with valves closed, you cut off the air, and remove either the exhaust or intake manifold first, and listen for air hissing out , if air is hissing from the carb side, intake valve or valve seat is toast. Sam for the exhaust.
If no air is heard in any of these spots, remove the dipstick cap, if you hear air hissing in the crank case, the rings are shot.
This video describes it well.
https://www.youtube.com/watch?v=l95j1pr7mg4