Verified answer

You will not find an aftermarket seat that will specifically fit your bike exactly. As with almost all the custom built bikes, your bike's seat was custom made to fit the bike perfectly, meaning it was moulded to fit the exact contours of the frame, fender, tanks and mounting/retaining tab points.

What is wrong with yours? You could always locate a custom bike shop in your area and have yours stipped down, repaired, recontour the padding and recovered, etc, or have a new custom seat made.