I know the stock Meanstreak seat is a nice fit. I purchased one off of ebay after seeing it installed on bikeronbudgets bike in the show us your VN750 thread.
the tongue groove fits, and covers the majority of the fuel hose port on the tank. but leaves a little room on the sides.
the only modification to the seat is the need to reverse the side mount brackets so they sit closer to the frame.
then all you need to do is drill and tap the side frame and the rear fender. the seat fits pretty well, there is slight pressure to get the passenger seat to stay flush with the rear fender, but not much. it makes the bike look pretty slick.
This would also be a good solution for a shorter rider as it pushes you forward, in my case, it moved my knees from the back tip of the tank wings to past the middle of them.
Much to close for my liking as I am about 6'3" with long arms, hehe.
So its not being used, sitting. at least it was a relatively cheap lesson. LOL. Hope this helps...