I think I have a leaking valve guide seal causing some smoke. I hope it's a valve and not the piston rings. Just to be sure I want to check the cylinder compression. Does anyone know what the cylinder compression should read on a 1964 390ci?

Would leaking valve seals effect pressure? Would this test really eliminate the piston rings, or would low compression be read even on a leaking valve? How can I rule one or the other out? HELP?????