Woah!! Dude, you scored HUGE!!
Ok, first you can prob look inside the hilt to see if it's wired up- with batteries out look up inside with flashlight and see if any wires attached to it?
Even if it's not wired, that's actually super easy to do
. The tough part of actually drilling the port in is done for you. You can totally find the cords you need- and those plugs/ cables can be made up for any power source. Like the 2.1mm plug end can be stuck on any charge cable you need. Perosanlly I'd just go with li ion cause better and really not a big price difference from nicad or whatever in long run.
If you ever wanna look into this gimme a shout
.