The mechanical advance mechanism is no different on the MP distributor than on the production/stock '72-up distributor the mechanical advance springs are anchored to the shaft by eccentric posts which can be grabbed with a pliers and turned to adjust the preload tension on each of the two springs.
The vacuum advance is likewise adjustable on both the stock '72+ and MP distributors, by means of a 3/32" hex key inserted into the vacuum nipple.