OK, now we are getting somewhere.
As far as I can see, your EFI needs separate ignition driver to work. So far so good. Second, your EFI cannot feed more than four coils, which means that you are forced to run it in waste-fire mode to make it work with your six cylinders.
It means that coils are firing twice as often. I suggest torrough examination of dwell parameters regarding this issue. Also, check with manufacturer of EFI/ignitors what coil impedance they recommend.
I personally believe that dwell-numbers are tuned the way that leaves ignitors feeding the current to coils for too long time, making them overheat.
If you find no other way of curing the problem, you can try adding the shunt resistor in series of each of three coils.
Thank you for your time,