You can chop the bolt as long as it is threaded all the way up to the brake. If it has an unthreaded section it might not leave enough threads to properly secure the nut to. If you do cut the bolt, wind a normal nut onto it first so that you can wind it off after you cut the bolt to clean the thread up.
If you can't cut the bolt I think I have a short pivot bolt off a rear Tektro brake that you can have for the price of a coffee.
You can chop the bolt as long as it is threaded all the way up to the brake. If it has an unthreaded section it might not leave enough threads to properly secure the nut to. If you do cut the bolt, wind a normal nut onto it first so that you can wind it off after you cut the bolt to clean the thread up.
If you can't cut the bolt I think I have a short pivot bolt off a rear Tektro brake that you can have for the price of a coffee.