OK, I dug around the garage and found a ballast that reads .7 ohms. Might be the one that came with the MSD coil, I dunno. Still seeing less than 5 volts at the coil! Went over the wiring to the ballast and the box, seems OK. Jumpered the ballast out, I get 8.3v at the coil, engine off. Was tempted to start it just to see, but didn't want to fry my only chrome box.

BTW, are ballasts rated hot or cold? The .7 ohm one read more like 1.5+ after running the engine a bit.