I thought all the MP distributors were either made by Chrysler or Mallory, but I've been wrong before.

If it's a Mallory unit, it's easily adjustable.

If it's a Chrysler unit, you either shorten the slots by welding or with JB Weld, then carefully file them slightly longer, reinstall, test, remove, file, reinstall, test, etc. until you've got the mechanical advance limited to what you want.

I hope that makes sense.