My take is that you either have to polish the entire bike or not at all (if you are a good enough brazier to pull that off) as if you just go 1/2 way it looks like a hack job, which it most certainly is......
Here, the area has been just brazed and needs to be soaked overnight in a dunk tank to not only remove the flux on the outside but the flux on the inside as well.
Here it is all free of flux but for the most tenacious flakes.
A nice braze, you could just spray a powdercoat and a clear on that and run it, which I offer, for less then a fully polished bike, and you will see why in the following pics.
First, some noisy ass grinding with an Aluminum Oxide point - Al-Oxides are better known to many as Corundum and with impurities as Rubies and Sapphires.......Some of the hardest elements we know of due to their tight molecular structure.
To look perfect and blend seamlessly one needs to have a nice uniform radius which compliments the area you are polishing. Here the weapon of choice is a snap-on rat tail file.
Here I have went over the area I am working on with these files - a 10" rat tail bastard (yep - cool name!) a 8" 2nd cut half round, and the tiny snap-on rat tail.
Now I hit it with some 3M 80 grit emery paper to see how it's all blending together.