I would call Green Mountain Barrel Company and see what they suggest about the tang. As for the hooked breech, it might be easier to take the differenceoff the barrel part. Otherwise it would effect the fit of the factory barrel. As for trimming the thumble rib, I did not remove it.Although there is not a lot to taking the thing off. I put the barrel in a vice and with a dremel tool and metal cutter disc, just went real slow until I was almost to the barrel. A little wiggle and it came right off. Then a file smoothed that edge out. Others might have done it different. If the screws would come out, you could do a better job of it taking it off.