John,
Your old distributor has been converted for use with the MSD, it too originally had a module in it. You will have to do the same with the ProForm one, but I would call them first and make certain you use the correct wires. Without a wiring diagram of the ProFOrm distributor, its hard, if not impossible to give you the correct answer.

 

Why gut a "new" distributor? Just keep using the old one. Rebuild or replace the advance mechanism, toss in a pickup coil if you need one, and put the Proform on eBay.

 

i've got calls into msd and proform. guess the're pretty busy this time of year.
i was under the impression that all of the newer dist. were compatible with the ignition boxes like msd.
i tried to repair the old gm hei, took it apart, cleaned and lubed it used new weights and springs. it's erratic as heck. sometimes i can really feel the advance kick in and others it's flat as heck.
i think a new dist. is the answer. thanks for the suggestions, john