Don't know what the confusion is here, it's a negative ground system. I never said it was a positive ground. The NEG of the IGN COIL goes to ground. The POS comes from the TIM. It's just a matter of choosing the right transistor or making it a flyback design. For an example, there is US patent 3,169,212 dated Feb. 9, 1965. It uses a grounded coil, has a flyback diode, and uses a NPN transistor that (through a capacitor) connects to the positive of the ign coil. In fact, I think it's the design of my module, or very close to it. Just found it on-line. Invented by Robert K. Walters. Invented in '61 but not patented until '65.
Thanks for the link, I could use that design. Would have to do some rewiring of the existing system, but it could work. If my OEM module is bad I might use it.