I believe there is an ignition problem: The engine will light off immediately but when the key is returned to the run position the engine will immediately die. Engine is a 1969 440.

Distributer is an MSD Pro Billet. I am not using a box and I am not using a ballast resister.
This distributer was used for dyno runs so I believe it’s functioning properly. Coil is MSD blaster. Both are new units.

The car has a new “stock” engine wire harnesses installed. On this harness there is a blue wire that connects to the “factory coil”. I have this wire connected to the positive terminal on the Blaster coil.

The only other modifications to the electrical system is an electric fuel pump. It is powered directly from the alternator stud through a relay. I’m using the wire that would normally go to the ballast resister, a single blue wire, as a trigger wire for the fuel pump.

Is the blue wire that would normally go to a stock coil constant 12 volts? Would the fuel pump wiring have any effect on ignition? What do you think might be causing this condition?

The problem is likely that you do not have the hot wire in the run position connected to anything. This would be the wire that goes to the "other" side of the ballast with a normal ignition setup.

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Is the blue wire that would normally go to a stock coil constant 12 volts? Would the fuel pump wiring have any effect on ignition? What do you think might be causing this condition?

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The coil (your blue wire) will not be a full 12V in the run position. It should have been stepped down by the ballast resistor to something like 4-5V. The full 12V gets applied to the ballast which is a resistor which drops the voltage to the factory coil. My experience with this coil is to use the MSD ballast resistor which is lower than the factory unit but this wouldn't be the issue right now...

This blue wire should have voltage when the key is in run or start. I think it may be full 12V when in start but not in run (reduced voltage from ballast). If no voltage on coil when in run, then likely a dud ballast!

If the positive terminal of your coil is getting voltage when the key is in the run position (even after engine dies), then it's likely not a wiring issue (move on to dizzy or pump). Also, make sure the fuel pump isn't cutting off somehow after the motor dies. You did use the right place for the fuel pump to tap into though!

Just tie them together. I have my GTS wired like that right now (it gets started about once per year or so) due to needing the ballast on another car.

Change the ballast resistor.