Re: cutting through the barrel flutes ?
I'm not a big fan of flutes in general, but my only concern with cutting through the flutes on a barrel would be with having a funny crown screw up accuracy. That being said, you're talking muzzle brake anyway, so it won't affect the crown. In reality, I think it should look good.
As far as barrel strength lost by cutting into the flutes, you're at the muzzle end, so rigidity isn't as big a concern as say. At the recoil, where leverage from the unsupported weight of the barrel and barrel whip harmonics are focused, barrel rigidity is more important. Not to mention, flutes reduce barrel rigidity anyway. A fluted barrel is stronger than a non-fluted barrel of equivalent WEIGHT, but not equivalent profile. Translation, by cutting flutes into an otherwise unaltered barrel, its strength is decreased.
Let us know what you come up with.
-matt