An airshifter may not fit easily after installing a bearing support. DME racing make an offset shifter that may help.
When instslling, it is easiest to leave all of the engine mounts loose, install the support, and then tighten the engine mounts. Applying a bit of antiseize on the sprocket nut where it passes through the bearing is good practice.
Be sure to tighten the sprocket nut very tight. I have seen them end up only finger tight when removing.