Fitting the box isn't going to happen until there's about 1/4" of that muzzle block left. You can get to 5-3/8" barrel if you saw the ass end off the grip safety. And you'll need to chop the shit out of the magwell. Which is kind of a problem for retaining the ICE insert, so just get an STI magwell and chop that.
I guess I just need to make it fit the box... Ti for me. With just the bull, and the solid Ti block the weight was similar to a tungsten sleeved barrel, over 9 oz and still a tracker. It now runs a bushing.
If I could build it over I would do the bushing again, but leave the dust cover and front sight block, and try to make it nestle down to the frame like the Limcats. That, and make it fit the box.
Either way, it seems pretty silly. No thread protector for you, but tungsten sleeves are G2G?
Except for that, it's golden.