340 Static Compression Numbers and Test Procedure

340inabbody said
Don't know anything about the internals of the motor. I will see if I can look into the spark plug hold but I doubt I will see any thing.

Success depends on the light and where the piston is located. I've had best luck with a single LED flashlight with a flexible connection to the battery.
Might see the piston number, the overbore, or at least the shape and the number of notches.

This one