If you have ever set up skateboard wheels you know that a small spacer is required between the bearings. This allows you to tighten the axle bolt without binding up the bearings. The Wheel also has a surface which the bearing bodies tighten against.

When I have done this mod I measure the opening in the IA brace and calculate how deep to machine the arm so that once installed, the bearings match that measurement. I then turn the inner sleeve with a step on each side deep enough that the bearings slide in and the sleeve is recessed about 0.01" on each end. Without seeing yours I cant say what would be required to make it work. I will try to post a little drawing of how I have machined the ones I made.

I have a degree as a Tool Maker and have designed progressive dies, multi-cavity injection molds and have programmed CNC mills and lathes for the last 8 years. There is always a way to get from what you have to what you want!