I'm not sure if you are specifically have your heart set on playing M&M in Fantasy Grounds, or just want to play a superhero game. But, I'll provide this information anyway, which you may or may not find helpful, as it is timely.
The full 65 book run of Champions 4th edition is currently available thru
Bundle of Holding at a steal of a bargain. You can either opt for the full thing or a reduced subsection of the collection, though I would recommend getting the whole thing while its available at this greatly reduced price.
Champions is a simple enough system that it could be run via MoreCore. I picked this up and I will be investigating the inns and outs of the functionality soon and will be working on a MoreCore extension or roll, if needed, in order to get things to work the way they need to.