About your Harry Stu comment - I'd say it doesn't matter if you're crossing his character with that of a pre-existing series... he's still a Gary Stu.
Gary Stus come about when the character is one-sided, ridiculously capable, and, more often than not, entirely unrealistic. That seems to fit the mold of this Harry here.
It's an interesting story, if only for the fact that you didn't go the traditional route to creating a Harry Stu (and, Honks is always good), but lessened by the fact that he seems to be a terribly single-faceted character.
Author's response
- However, since he is totally in character for the crossover, he is not a Stu, Gary, Harry, Barry or otherwise...