I have been through this stuff myself. I really am thinking that maybe all you really need is another Jacobs K4 key and that maybe something is messed up with the one you have. As for your idea of installing it on a Milwaukee 1663 drill that's going to be wild but it sure can be done. I might add that the 1663 is one nice 1/2" rated spade handle drill and especially with the electronic speed control. Please don't overload it. What size shaft do you need to rotate? If a 5/8" chuck would work, those don't cost near as much as a 3/4" one. This is just in case you can't find a key that works. Anyway, I really would try another K4 key and let's hope this one does work. I have some other old timer chucks and have never had the kind of trouble you seem to be having unless the key was either defective (it happens now and then) or it was worn out. Is your chuck drilled and counter sunk for the retaining screw? If you'll only need to run the drill in the forward direction then you can forget the screw. I will add that to remove the chuck later on and to remove the current chuck, get a good 3/8" long arm L shape hex key such as ALLEN or EKLIND which are USA made. Tighten the jaws on the short arm and then strike the long arm with either a rawhide or hardwood hammer or a block of wood. Never strike tools with a steel hammer. They can and do bust and you end up hurt. Please do not use the chuck key as a chuck remover tool. That's a good way to mess up the holes in the chuck body and also bust or bend the pilot pin on the key. Good luck with your project and please post updates. Now I'm off to see your pictures.