77 KZ650B1 Stepped Seat Cover

Hey all, I'm looking for some help identifying the seat I have on my 77 KZ650. I want to put a new cover on this, but the only 650B1 covers I can find are the flat seat style. Would a 750 LTD seat cover like this ( www.z1enterprises.com/seat-cover-kawasak...4-ltd-1980-1983.html ) fit?

Here are the dimensions that make sense to me, but I can definitely remeasure and include other dimensions of the foam.
Length: about 29"
Width: widest point about 11"
Thick: roughly 3" in front, 5-5.5" in bac

 

The 750H seat is different & I don't think that seat cover will fit right. 
I don't know if your seat would have been a Kawasaki option or aftermarket.
The KZ900B/1000B Ltd models had similar seats to yours but I have no idea if a seat cover for one of those would work.

Looks like a KZ900/1000 LTD seat foam.

 

This is what I got.
z1parts.net/seat-cover-1976-1980-kz900-kz1000-ltd/