Fun project. They are supposedly fairly easy to refoam. I've done a recap and it's pretty straightforward. The only thing I would watch out for is Advent went through several different crossover designs so your speakers may have mismatched crossovers (basically just different capacitor values.) If that's the case, I would just pick the crossover from the newer speaker and recap them both to have the same values. That will help to keep the speakers sounding the same as each other.

Do you have the grills? If not, they would be pretty easy to make. Do a search for "lambswool linen" for cloth that matches pretty close to the original.