A couple of thoughts..
The MSD boxes need voltage to run. Regarding the alternator, a trick we have run on some of our cars is to switch off the alternator's Field lead..

EZ to install a simple toggle switch in series for the Field wire lead, turn it OFF when rippin down the strip. Turn it ON to keep the battery charged. Many people don't realize how much drag the alternator pulls while charging..

Just my $0.015...