I circled back with Ed who told me that the wider (non-spacer) caliper in Brake Kit 1 is indeed a new design. Dimensions are identical to the stock caliper, including same piston diameter, but the width is obviously increased. It was/is produced by the same UK company that made the stock D calipers.
I am impressed that he produced a new casting without much fanfare or promotion. He just went ahead and did it.