Why remove the pump, don't you want that cold A/C when your racing? Since it's all aluminum I can't imagine it's worth the weight savings, as long as it's turned off you shouldn't have any drag on the motor, it's basically a dead pulley already...
Otherwise have a local machine shop make a pulley, but I bet MBZ sells one, you just have to find the part number.

Have you installed the Schricks racing cams on the crossfire yet? For all the energy of taking the A/C pump out and making a pulley your probably better off installing the higher lift cams.