Msd ignition plug gap ?????

I would definitely try .050-.060 with your set up. If you were running boost, then I would stay where you are at, or go down to .025-.028.

The whole theory behind the multiple spark discharge, is that you can supposedly run a wider gap because of the hotter spark. Going wider on your gap, may in fact clean up some of your issue.

Your car is sick, by the way!!!