If you use deepwell sockets wrapped with 320 sandpaper it shouldn't take much work to get you close. Finish with a finer grit (600). You might need the dremel with a drum possibly in the barrel nut area but most likely not. Go slow with the "socket" sander and check with a paper strip often for full float.
Of coarse you can't get started until you headspace the barrel and tighten down the action.
As mentioned before the lack of patience often gets us in a bind. But your progress so far
combined with patience is going to leave you with a nice end result!
Hope others would join in and offer more of their expertise.