The Fuzion Pro X3 has a threaded fork and headset and uses standard diameter bars. The District Brandon James bars are oversized for HIC so they would not work on the Pro X3 without replacing the fork and the headset and converting the scooter to HIC.
If the clamp bolts are stripped, you'll have to cut them off or cut a slit in the head of the bolt and use a flathead screwdriver to try to get them out. You may need to replace the clamp. If they are just very tight, try using an allen with a different form factor, like a T-handle.
It might fit, but I wouldn't count on it. The only way to know for sure is to try it with someone's. I definitely wouldn't assume that it fits the same as that part of the deck and brake are not standardized across brands.