Rick,
we did more or less the same to our Clevelands.
During the winter I installed a MSD Digital 6 with rev limiter and 20 degrees start retard because of my high CR.
The advantage of the Digital 6 are the dials for the rev limiter, no pills are needed and you can choose between low and high CR setup generally.
The box is installed along with a Holley/MSD Magnetic Pro-Billet Distributor and a Holley coil but I will change to MSD Blaster HVC coil.
It sits upside down under the co drivers footwell.
Till now everything is fine. The same results as You described for the 6AL.
Clevelands rock, Greetings from Europe,
Uwe