what is the deal with my 225 /six compression?

i picked this car up about 10 days ago for $500 not running. after cleaning gas tank/lines out, new fuel pump, cap and rotor, wires, rebuilding holley 1920 it started right up. i then was told by a friend that a cylinder pressure test is a good way to check the health of the engine. i took the plugs out and come up with these readings.


cylinder 1-150psi/10.4bar
cylinder 2-132psi/9.3bar
cylinder 3-145psi/10.2bar
cylinder 4-140psi/9.6bar
cylinder 5-142psi/9.9bar
cylinder 6-130psi/9.0bar

1966 Dodge Dart 270 4 door.
i honestly am new to working on engines, what is the mathematical equation to figure out what these numbers mean?