I should have said ignition system. The light I had was a relatively new unit with an inductive pickup. If I remember right the distributor was a Mallory electronic crab style.
I had that happen a while ago. My timing light that I had been using would not work on an engine with an electronic distributor. Borrowed a friends light and it worked perfectly. I have both a Sunpro and a Snap On that work well.
I think you have something wrong if you only have 55 psi compression. Do a cylinder leak down test to determine where the problem is. Try oiling the cylinder walls and retest to see if the compression comes up.