You might notice the extra hole near one of the bolts for the motor face. Oops, the dummy running the mill forgot to zero the x & y axis before moving to the position for the first hole. To cover my mistake, I ended up rotating the bolt pattern 14 degrees, so now the chain will have less clearance for the mounting bolt closest to the swing-arm.
I'm also not thrilled about the flanges I bolted on to provide a clamping action around the motor, as they look a little cheezy. I would have been better served by a couple of pieces of 3/4" x 1" aluminum stock.
Another lesson learned: plasma tends to cut features about .075" smaller that drawn, so I ended up doing a lot of handwork to enlarge the internal diameters on both brackets.