Tail plastic, seat mod?

Ok so here is my question. My 83 KZ 750H has a good seat on it but I am not sure if it is the original. It seems a bit big. I am really interested in adding a tail piece to my bike and maybe eliminating the rear fender. I have already moved the rear fender up a little so the tail light is near the seat. Will I have to cut hte seat pan down in order to put a tail piece on? Here are a couple of pics I took today so you all can see what I am talking about.

That's either a non-OEM seat, or it's really been worked over from what it originally was.:pinch:

It should be more of "stepped" seat (higher in the rear for the passenger), and having been smoothed out like that just might be why it looks longer.

It should look like this:


I'm sure the frame rails are different between the models, but with a little fabbing and "massaging" to those frame rails, you can swap over to the seat and rear cover like this from the KZ750-E model: