After 4 months of frustration, I finally got the MSD EFI running the week before the 2023 Mustang show in Canberra.
I had the tach signal wire from the MSD connected to the ICE tach wire as per the MSD and ICE instructions and it would fire up once and then shut down. I tried everything, even put the carby back on to check it worked, and it did.
Finally, I rang my mate who sold me the system and he said 'ignore the instructions, run the msd tach wire directly to the negative of the coil'. I did it while he was on the phone as I was leaning over the engine bay and it fired up and ran!
I'll be blowed!
Did 180k in her last week in 2 nights.
I took her out to the Mustang Show at Erindale last Sunday. Away this week but when I get back I'm just going to drive the doors off it for a while and enjoy it because it's been off the road more than on the road in the last 5.5yrs of ownership.