After a little searching it appears that the brand of bars makes a difference. For instance, I have some steel Nittos with plenty of clearance, but I wanted alloy.

I knew it was close, so I started by using a grinding wheel on the bolt ends...that job was quick and easy. Next, though, I had to relieve the inside curve of the three pawls, where they contact the bolt, since they were also too wide to insert. For that I used a round cutting bit in my dremel, which took a bit longer, but eventually I was successful.