Dented freehub - how to straighten?
 

The freehub on the 135 MTB hub I want to build has a slight (about 3/8" wide) dent in the end of the freehub where the cassette keeper screws in. It looks likd the hub might have been dropped?

I need to recurve the dented section so I can use the part. Obviously, some brute force and awkwardness will be required (boy can I supply :D ). What is the best way to do this repair?

Back it with a block of wood and use the ball end of a ball peen hammer. Gentle taps, not heavy blows.
You will need to take it off the hub or at least remove the axle to get a clean shot.
If you mess it up you can use the one off of your 130 wheel (assuming both are Shimano) or get a new one for about $30