One of us has the brackets between the cam arm and the chain wrong too. That's another important one to get right. Yours has the bend in the bracket going "out" and mind going "in". I think it just needs to be turned around.
I think they should look like this (someone please jump in and verify yes/no...)
Also above, when I mentioned that you would not need to clearance the backer plate on the inside of the DC mount - I think I may have been mistaken. If you have a mount like the one one the LEFT you don't need to clearance a backer plate. For one like the one on the right you do.
For the right hand one - even when you clearance the backer plates you may find that the inside and outside are tight to the frame but the center is not. There's not much you can do about that.
