For the rear brake, it's not necessarily the caliper itself. I went to the HD Full Floating rotors and Lyndall racing pads... whole new animal now.
Front went to a floater also with a GSXR 4 pot Tokico with Vesrah Sintered pads.
The Sportster actually stops now.
Although I'd still like to try dual Tokico 4 pots up front... Still waiting to find a good deal on a set of dual disk sliders.