If you choose to sand the bottom of the conrod, take as little off as possible and make sure the surface finish is free of marks, ie, no scratches from the sanding. Scratches are a point source for cracks to start.

Also, I'm wondering if it is possible that the aluminum case will expand enough when it is operating (warm) so that the interference goes away. Aluminum, especially with a larger diameter, like the case, will expand a surprising amount when heated.

Jack