Unknown Pedigree - What Model am I?

Here is a question for the old pros who know these bikes in and out. I bought this bike a year ago and have been slowly bringing her back to life and making her beautiful again. She is a '79 650 but I don't know which model she is. She is registered as a C cause that is what the frame says, but the engine block and mufflers are both from a B (though not the same one). My main point of consternation comes from the tires (alloy rims, not spokes), and the seat (two tier style). I am not a purist and will love her no matter what her heritage, I would just like to know which model she most closely resembles so I know how best to describe her. Here's a picture of the old girl:

i dont think that seat came stock on that bike,the wheels look right but front fender looks odd with those wheels

Looks like someone put the alloys on it and God only knows where that seat came from. Looks comfy tho.

You have a 650 C the chrome fenders, larger tank and the fact that it has a tail section disqualifies it from being an SR. Also since it has an 18" mag wheel and triple discs that would also make it a C model. Plummen is correct that is not a stock seat, it should have a seat that looks like an ironing board.

Yea it's a 1979 KZ650C3. The seat as mentioned is not original. It probably had big sissy bar or saddle bags at one time because the grab rails are missing. The KZ650C used KZ650B serial engines and pipes, so those may be original.

This is why I love this site...experts at your disposal 24 hours a day. Thanks for all of the responses, it is nice to know that I am not the only one who was confused by that seat. In answer to the question earlier, no it is not comfortable. I am 6' 5" and have to sit on the hump of the seat to keep my knees out of the handlebars. After I am done with the exhaust (I will post pics on that one in the project section later) my next project will be to somehow mod the seat to make it a bit more friendly to the vertically gifted like myself. Any ideas or suggestions would be welcomed.
Thanks again for all of your help in identifying my baby!