Actually Ghost in the Shell vs. Lupin wouldn't be bad at all, in fact that's actually a good idea, but if the GitS universe in there were like the manga's universe the comedy would work better
I agree, I'm no big Detective CONAN fan either (since I prefer YAIBA and Magic Kaitou, Gosho Aoyama's earlier work), but I think this should be interesting, and I hope the special turns out good, since with crossovers it's an "either or" situation