I bought one of those Vietnam seat covers off eBay for $150 (free shipping, haha). It said it would fit a cb550k from 74-77. I thought it seemed a little fishy. Well, my bike is a 1977 cb550k and as suspected the cover is not long enough. Can I trim the seat pan so I can still use the factory seat lock and hinges and my new cover, or is the frame itself longer at the hump too? Meaning, if I trim it to fit the new cover the seat won't cover the end of the frame?