Gus - Thanks, but remember I'm not an expert at this, I'm just putting my opinion out there.

cme469 - That is the method I used when I installed an HEI. The original resistance wire supplies plenty of voltage for the control circuit to switch the relay on and off, and the power circuit running from a junction supplies battery voltage at start up and full 14.8 volts when running. That eliminates the yellow wire going to the coil from the R stud on the starter.

Mark - If you have been running with this set up for a while and this problem has just started, check for a short to ground in the wire itself as well as a shorted primary winding in the coil. From what I've been led to believe pre around 2001 MSD coils were made in the USA. After that the red ones were made in Mexico. The Mexico ones were rumored to have problems with shorted windings. The old ones had a ribbed body the newer ones are smooth. If the windings are starting to shorten out it may cause the coil to completely fail or cause wiring to pass too much current and over heat. I just took a brand new MSD Blaster 2, PN 8202 out of the box and tested the windings. It's made in China.
The primary winding has a resistance of 0.7 ohms. the secondary has 5,220 ohms. Specs are 0.7 ohms and 4,500 ohms.
The Blaster 2 is made for use with a MSD ignition box, if used with a normal points distributor it need a 0.8 ohm ballast resistor.
Hope that helps.