I don't think they've made a barrel nut for it yet. I'd imagine it would be easy, their design is pretty simple.
I had the Delta style in my MaTen. I really like that handguard. Almost got it again for the Armalite, but decided against it. Was trying to go for a semi affordable build instead of balls to the wall.
I'm waiting for receiver sets, carriers, and third party barrels before i get into the GII platform. My armalite is still manageable, not any more cumbersome than my AR15. Both are 20" barrels, the AR10 only has 1.5lbs on the AR15 unloaded. Can't tell the difference when picking them up, but the AR10 is more center heavy. It's balance better. My goto AR15 is a little front heavy. I held a GII hunter i think. Whatever the 20" one is, and it felt just like my 15, a little front heavy. Would be fixed with a different stock.
In itching for another build. Too many choices. Is either a pistol caliber AR, a short duty driven 308 upper, maybe 338fed upper in 12.5", or something else entirely. I would love a compact 338fed in the GII.