No spark- what am I missing?

It won't hurt to run the engine w/ 12 V to coil+ w/ a jumper wire for a short time (<2 min). Eventually, the coil will get too hot like that. That test bypasses the whole ign wiring. Also, connect your spark tester directly to the coil HV output, which bypasses the distributor's rotor & towers.

If still no spark, I would remove the distributor and spin it by hand to check things. You will need to ground the distributor's case to BATT-. If still nothing, remove coil- from the points and make your own "points" by touching a jumper wire from coil- to BATT- and releasing (mentioned in post #14). That tests the coil alone. Do not touch that coil- wire with your hand or you will feel high voltage.