Another maple grafting question.
 

I have a bunch of maples growing around my house, but they all have
leaves the size of a dinner plate. Not exactly good bonsai material.
However, I found one with a nice trunk about 4 inches across at the
base, and now I'm wondering if I could graft a more bonsai appropriate
species of maple onto it. Is that possible? Or do they have to be of
the same species?