The M.P. springs never come with directions on how to use them. You can put two on one post( by stretching them together and letting them alternate coils), and leave the thick slotted factory spring, for leaving some give, for upper RPM's to compensate for cam stretch. Or one on each post if you weld up the slot to limit total. the problem here is bouncing and retard of 2 degrees at 6g.
I welded the full advance side of the slot to give 18-20 initial and 18* movement for a total of 38* and used the slotted factory for the total limit. The DC. manual eludes to this use of the slot for what I just wrote. The old HP euc/ dist. kit has the softest factory small and the slotted spring has the shortest slot of all that I have seen from dismantling many Mopar dist. I had some floating too at idle, so I added one weak one to the slotted springs pegs. If the advance is too quick the car may overheat, since your at the edge of detonation. That plate product looks good to use instead of welding, since you can do it yourself. You can use a food scale to gauge the ounces it takes to pull the spring out, then you know what each different tiny spring is worth and figure what you want to do next. Tape a paper clip on the scale and use a ruler to gauge the stretch by hooking a tool such as the set from Harbor Freight. Those hook tools and a thin flat screw driver, are great for sneaking the spring on and off. But first remove the vac. canister to be able to work from the side and top. I can post pictures if someone is confused.
I'm now trying to tune one of those $50 billet copies.
I had to bend the limiter tabs to limit the total and add a weak spring to slow it down. (procomp has the caps and rotors for them if you want the old style cap for $5.)
Who sells the plate kit?