It's been a hot minute since I posted this, so I can't remember the exact setup I was using, but I tried it again this evening and it seems to be working now. Idk what that was about. I guess it's some sort of compatibility bug with one of my other countless mods. While I'm thinking about the menu, I think it'd be a lot better if it just displayed more info. Like for example, all of my equipment instead of just the ones I have equipped in the moment.
If you're going ahead with this, I also agree that a rifle and/or railgun type weapon would be really good. I'd still prefer a super-accurate shotgun, but they're basically the same thing as a rifle. Alternatively, you could give every weapon an alt-fire and have a high accuracy shot be one of them. Alt-fires are always really cool. It would also be nice to see one or two hexen weapons.
Also, cool feature idea. Crossover compatibility option with the DamNums mod to show when you score a critical hit.
Edit: Discovered a very funny but impractical bug: Reaching level 303 makes the experience stack overflow, causing it to go negative and prevent any further level ups. You will never reach level 303 without using commands, but I found it amusing.