Ballast Resister Needed?
For the OP, do you mean the ProComp PC2015 6AL? If so, no ballast is used. In fact a certain coil looks to be needed: an HEI type with a primary resistance of under 1 ohm. In other words, you can't use the stock type coil. But the documentation on this system is very poor.... I can't find an specific info on the coil requirements. So far, I can only conclude by inference that is needs the HEI type of coil with low primary resistance, since that is what is sold to work with it.
And understood on the money... but we are ditching an almost new Profrom dristributor that looks to be changing its timing rather randomly. My son ordered a complete HEI kit from Trailbeast. With a nice engine like your 408, IMO there is no sense in crappy things like erratic ignitions and leaky carbs. As an suggestion for you, you might consider selling the Procomp and getting something better.