Either the foam on that ducktail seat has been cut down (and poorly) or that's a K0 seat cover on a different pan and foam. Either way, it's not worth as much as an unmolested example.
The stock seat is in better condition and looks better on the bike. Besides, a K0 seat on a later 750 just doesn't look right IMO. Not that I'd have a problem using one if that's what I had, but if I had the choice I'd use a later model, stock seat.