Torrel Disc conversion - calliper won't fit.

I've been rebuilding a '67 Series 2A and had bought the Torrel disc conversion kit some years ago.

Now I'm trying to fit the callipers and I believe I've followed the instructions correctly but the calliper frame won't fit between the mounting bracket and the rotor.

Anyone else had this experience? I just don't see how I could do anything differently to mount the frame onto the bracket. (I know the brackets go L->left side and R->right side and the callipers go to the opposite side of their markings (i.e. L->right and R->left) but it doesn't change the fact that there simply isn't enough space to position the frame in the gap between bracket and rotor.

Post some pictures, if you can. Not promising I can help, but maybe if we see some pictures - someone else on the forum might have a bright idea?