CSR to kz650 conversion

First time poster here, been lurking for a few months since being gifted a 1981 KZ650 CSR. Was mostly focused on getting it running, now that that's out of the way I realized that this is a CSR model. Didnt realize until now on account of there being no seat or badges left on the bike.

I got excited about this bike in the first place because Im fond of the 70s/80s japan import cafe racer aesthetic. I dont hate choppers, but Im really not that into choppers with inline fours lol. On top of that someone has hacked the rear hoop of the subframe off and welded it back on like a sissy bar!

Anyways I found a nice 79 kz chassis close to me for less than 200$, but I havent gotten a response back from the seller in a couple days. I'm wondering if I could just throw an 18" rear wheel on my CSR? seems like it would bring the aesthetic more in line with what Im looking for, just worried it might not fit.

I almost did that with my '82 KZ750 Ltd. Almost the same bike just, 100cc bigger. I did put a rear 18" wheel on and it is 2" taller. I looked at it and thought,If I had 1" taller shocks it might work. With the taller wheels you lose that much clearance and might hit the fender if you bottom out stock shocks.