"..the only problem I had with it was that it wrecked my plans for a fanfic..."
Really, if Alan Moore let "someone else had this idea before" stop him, we wouldn't have very much Alan Moore, now would we? ;-)
Chronologically, I can't see how that team could work when decades separate Jeeves and Lugg from Pennyworth and Jarvis, and then decades more before we reach Parker's era? (Unless perhaps you used an East End ancestor of Parker...) But I'd like to see it!
Agreed on "What Ho" and the pre-Fireball XL-5 stuff being the best parts of the Dossier.