Internally geared hubs require a 135mm dropout spacing, and the old Schwinn 10-speeds have a 120mm dropout spacing. since the bike has a lot of rusted parts already, I would say that this frame is a very poor choice for such a project. spreading these dropouts will likely result in catastrophic chainstay failure. Besides, it sounds like you could buy an entire bike for less than the $$ it's going to cost you to put this thing together. Once it is built, it's still going to be on an old, cheap, heavy, worn-out frame; what's the point?