Stock swingarm Rim/tire accommodations

I have a 1977 KZ1000A with a stock swingarm and spoked rear rim, also stock. I would like to put a wider rear on the bike. Does anyone know how wide of a tire/rim will fit? I would not be opposed to lacing a wider rim on a spare hub if anyone has experience with that also.
Thanks
LS

When I looked at the clearance on my swingarm there wasn't much room for a wider rim. Not sure how much wider (if at all) you'll be able to go. It's the front of the swingarm (near the mount) that has little to no clearance with a stock or 120 or 130 tire.

3-3.5 rim with 130 tire is about it

Thank you both for your simple black and white answers. This saves me a lot of time.
LS