It looks like the Progression Ignition distributor does not need a tach adapter. It installs the same as the stock distributor and the tach is connected directly to the negative side of the coil as done by the factory.
Progression Ignitions also provide a wire (it is grey) to feed tachometers that need a square wave signal. I am guessing that the MSD box tachometer output does the same. And it looks like this square wave output needs a tach adapter to work with our tachometer. Thus, we disregard Progression Ignitions' grey output wire when installing in a Pantera and simply connect to the negative side of the coil.
I received one these distributors today and I am planning to install it tomorrow. It is going into a Pantera that has an MSD 8577 distributor (I need this distributor for another project) and an MSD 6A box that will go onto a shelf. I spoke with Progression Ignitions this afternoon they confirmed that it will work properly with my MSD Blaster 2 coil. The factory wiring needs to be resurrected for this to work. I will report back with the outcome.