Taller Rear wheel for 82 KZ750 LTD

Hi, Trying to figure out if there are any options to fit an 18 inch rear wheel on my 82 LTD h3. Trying to turn it into more of a Brat style build and need a larger rear wheel for the variety of tires I prefer. Bear in mind this is my first bike I've modified but honestly for what I have into it it's lovely, Threw in a Pic of the bike as it sits currently.

From the edit by the moderator, it seems you didn't click "insert" on your photo before posting.  

Anyway, what about an 18" wheel from a 750E?  

I have the same bike. '82 KZ750L. I mounted an 18" wheel from an E, because I too wanted to have a larger rear tire.  No problem in the mounting of the wheel. I put the stock mag back on because I feared the stock shocks would be too short. I think if the shocks were 1", 1 1/4" taller it would work. Reason being ,the 18" wheel & tire is 2 inches taller..

From the tire number math the 750E stock rear tire should be a little more than a half inch taller than the Ltd.
If a 120/90 tire can be installed, then it'll be about 1.3" taller.