what voltage should I have at the coil

I tried this and you can hear a spark but you cant see it in the spark tester I have. I remember this same vehicle producing a visible spark before with the same tester, so that means there is a spark but a very weak one.

This might be a clue. Abandon the spark tester for now. "Rig" a probe out of what you can. That is, use a grounded clip lead to something like a screwdriver, grounded to the block. Hold the probe near the top of the coil tower. Either spinning the distributor, or grounding the proper wire at the distributor harness connector should produce spark