don't bevel the flat side of the single bevel...counterproductive.. now on top of the angled side you have to worry about keeping a second angle correct on what makes it a superior cutting tool- a flat side.
You don't need to go through all these machinations.
Simply flatten the flat side first, by laying your 12 inch flat bastard file on the table and drawing the flat side along it until you see that you have removed paint and indeed can feel it is flat with your fingers.
Then take your same file and holding the head against the corner of a table, or stair railing, or whatever you can hold it against that will allow you to keep it rock steady, push the file from back to front, without using much pressure, along the edge until you see what I call the 'foil' edge form.
Flip the head and do the second side, then move to a piece of cardboard, rough side up, laid flat on the table, and 'strop' the broadhead back and forth on each edge until you see the foil peel off like an apple peel- it'll curl up and come off.
At that point- STOP. Anything else you do is going to be counterproductive to that edge.
Put some chapstick on the blade edges, put them in your quiver and go kill something.