Bill, just to give you an idea on a front brake conversion cost, around $300. This includes everything from front hub, shoes, backing plate, brake lever and cable. Those front hubs are pretty hard to come by. You could convert a rear one, but it would take some machining. You would need to narrow it 1", and then slot the holes for the spokes on the small side. You need slots so you can angle in the spokes past the brake drum side.
BTW Mike, didn't you say you were a machinist?
Rick