Can I take the standard recess nut and grind part of it away on my bench grinder?[/QUOTE]
Why not shorten the bolt? Grinding the nut may destroy its shape and threads.
I mounted a Shimano R600 on an 1980s Miyata fork. The pivot bolt was about 2-3 mm to long, thus interfering with the brake mechanism (even after using spacers!) so I hacked off part of the bolt to provide more clearence. No problem.
A suggestion that was passed onto me via this forum: before you hack away, put a nut a few turns past the point where you will make your cut; after you cut, wrench it off to ensure a clean thread.