It is an outside possibility that you could find and axle that can be resplined to suit, but it's going to finish up a lot more trouble and only save $100. If you can pick up some C-body axles, get the retainers and adjusters off them (nobody seems to want C-body stuff), get the cut-to-length axles, use original tapered bearings, you can use original or '65-on drums and brakes. Or the '63 brakes if you can get the drums off readily.
When I think of it, if you pick up a complete C-body rear end drum to drum, that will give you 11" x 2" brakes, the retainers and adjuster, a spare centre pig and other hardware. Then just hang on to the empty housing till I come by and I'll take it off your hands.