A wider stock mag for the rear?

Curious if there is a wider stock style mag that could be put on my 78 KZ1000? I don't know what stock width is but assuming maybe 2 1/2? Is there maybe a 3 inch wide LTD style mag? Has this been done?

3.0"

Pretty sure it was ZR 1 mag

If you use a 16" LTD wheel, there will be more room for a wider tire.( I've spooned on a 150.) With a stock swing arm, there isn't much room for more tire with a stock 18" rim. 130/140? 80/18. You'd need a wider swing arm also. Several outfits widen the stock rear wheels. If you go over to a spoked back wheel, you can easily convert to a wide rim. Many have adapted later, sport bike rims. You'd have to make up some spacers. And again, you'll need a wider swingarm and probably an off set front sprocket to keep it all aligned.