This is where I misunderstood what you were using NOW I see "whut."
See that distributor is a stand alone ignition system all by itself. "It works" much like the Mopar ECU and an HEI type system, AND points. That is, it works by feeding 12V to the coil, and switching the coil NEGATIVE
So when you then add the MSD CD box NOW what you are doing is removing that "ready to run" system from the coil and using IT to trigger the MSD box.
I hope you are wiring it as figure 10 of the 8388 destructions, and you are right, the white is what should be triggering the MSD box
http://www.msdignition.com/Products/Distributors/Chrysler/Ready-to-Run/E-Curve/8388_-_Chrysler_318-360,_Ready_to_Run_Distributor.aspx
For testing you SHOULD be able to hook up "just" the distributor and run it
