Didn't read all replies ( and I bet is not necesary ), but just a note.

With MSD you can keep or not the ballast. If you want to get your system back to stock look and work ( with stock or HiPo Module ), would be easier keep it, instead hack up everything.

MSD would use the coil wire ( the one coming from ballast and the one they advice to use in fact ) to be turned on or off from ign key, so a small ~9 volt signal is enough to keep it on, and ballast will be cool anyway ( not much load required for that ). MSD won't use this source to power the ignition system. It already got the thick red wire coming from batt source for that.

Coil won't be sourced anymore from ballast, but from MSD itself, which being multispark ( "multitriggered" ), will keep cooler than a constant source from ballast/ign switch circuit like previouslly was.