I'm glad you found interest in my concepts. What you're looking for might be more easily adaptable from my old game
Evolution of a Hero. The old data is in the spoilers.
In the Superhero case, you don't really have the same limitations I do with Heroscape from the figures. Since in a Superhero version you wouldn't really change classes and races, its just a straight forward choose a Hero, choose a skill or two, level up, stats go up, get new abilities.
As for extending the campaign, its really tough, because a plus 1 to any stat is a lot bigger jump than in other RPG-style games. If most powers are 20-sided based, then adding 1 their roll is the smallest increment possible in Heroscape.
Since I've been working on this RPG thing since last spring, I know all the ups and downs, so I'll be sure to stick around and help you out.
And thanks for the advertising!
~Kaiyu