I just saw this thread on the weekly email I get from the forum on popular threads. As soon as I read the beginning of the thread I was almost 100% sure that the issue was with the magnetic pickup gap being too wide. I used to sell a ton of MSD boxes back in the 80's and 90's and I ended up having to diagnose a ton of no start issues. One thing that happened all the time was that customers would install an MSD box on a car that was running perfectly and as soon as they installed the box the car would not start. We would check the box and it was working fine, and the installs would also be correct. The issue was with the magnetic pickup gap being too wide. It seems that the factory box can pick up a signal if the gap is a bit too wide, but the MSD box could not. So, your car could have the pickup gap be twice as wide as it needs to be and still run fine with the OEM trigger box, but it will not run with the MSD box.