It really depends on how large of a modification you are willing to do for a windage adjustable rear sight.
I dont know about the BAR sight but the 1919A4 sight would be a great install but it would require you do drill out the mount holes and you would have to weld the adjustment disks to the rear sight housing. I am willing to bet that you would have to weld the adjustment bits for a BAR sight as well.
Once it has been decided to fight, one should do so to the very end, to conquer or perish...... Nothing smells better than the body of a dead enemy.
The meek shall inherit the earth - in little 3x6 plots Robert Heinlein