I believe there was someone awhile back that had this style of rear covers on their pumps, cam stock on a 525SC engine. A quick look on the internet showed that MIAMI MARINE SPECIALISTS, 1950 N.E. 135th St., North Miami, Fl, 33181
Phone (305)945-7997 | Fax (305)945-3675 has one in stock. I recently convereted my standard pump cover to something similar to you current stlye by installing two 90 degree barbed plastic fittings. Hope that this helps.