I also used some scrap flat stock @ 1 -1/2" or 2" width. I cut the flat stock slightly longer than the mounting hole width, and ground off the corners to prevent sharps. With the flat stock oriented horizontally, I drilled 4 holes, sprayed on some black paint to make 'em purty, then used button head bolts to make for clearance at the tire side and acorn nuts on the outside.
Note - your crossover brake line and its ability to snap back into the fender mounted holders* is an important consideration in this project, and the stock length line may require replacement. Spiegler makes custom sized brake lines.
http://www.spieglerusa.com/cfm/customline.cfm?type=std&email=yes&nlines=1. Their advice to measure with a piece of stiff wire is a good idea, for once the hose ships, it's yours. No returns on custom lines.
Someone on this web site had a very easy way to do all this with minimal work and modification, but I can't recall who or what the deal was. Hopefully they'll jump in and post their remedy.
*without these holders, the crossover brake line will likely chafe the paint on the fender. If chafed paint is not a problem, the stock line might(?) be used.
Pictures of fender mount mod For the sake of my frail ego:
The lockwasher in the wrong location is in service as a spacer. It was thickerer than a cut washer.
Edit
I just recalled - the factory fender bracket on mine needed to be at the full width of the forks to prevent rubbing the tire.
