Today the UJM seems to have disappeared from the marketplace, unless I'm just not looking in the right places. All I could find is this:
https://www.kawasaki.com/en-us/motorcycle/w/retro-classic/w800?cm_re=GLOBALNAV-_-PRODUCTGROUPLIST-_-MPP
That's the right styling, but I don't really need an 800cc engine, and I'm mostly interested in fuel economy for commuting to work, so a similar style bike with a smaller engine (maybe around 450 to 500cc) would probably be ideal. Does such a thing exist?
A couple other bikes that come to mind that might suit your styling preference as well as displacement and power range:
1. Husqvarna 401 Svartpilen.
Yes, it looks a little modernized and spacey. I didn't like it when I first saw one a couple years ago, but it's grown on me. I'm actually a little disappointed that Husky discontinued the Svartpilen 701. The 401 is high on Youtube's "YammieNoob" channel as a first bike, or a fun commuter/play bike. If I ever come across a 701 of these used for a good price I'll probably snatch one up. Heck, maybe even the 401. Its power is exactly in the right place for enjoying this bike in real environments, not race tracks. It will be lively and fun for rural highway carving, nimble in urban settings, and capable of Interstate travel though I would not encourage a cross country trip on it. $5400 new.
Honestly I can't encourage you to look at this bike enough.
Husky also has "Vitpilen" bikes which have sportier handlebars and a more aggressive rider position. I like the Svartpilen more, much closer to UJM/Scrambler position and style. I'd really like to see a Husqvarna "Norden" style 701 adventure bike, aiming for a high-300 pound weight range, with an aluminum or steel subframe rather than the 701 Enduro's plastic subframe. Give it a 250 mile range with an appropriate sized tank put into that metal subframe (the 701 Enduro's rear subframe IS the gas tank, making pillion use or packing luggage stressful on it) and it'd outsell so much.
2. Royal Enfield Himalayan.
It's not a rocket. But it is a tank. 400-ish cc, I forget the exact size. Its power is all torque. Yes, it'll do 80mph if you need it to. It excels in the 30-50mph range, but it can pick its way through scree very well at low speeds, and low speed handling is something oft overlooked with motorcycles that is a pretty important trait once you own one. RE is introducing a scrambler version of this bike that will have a smaller front wheel for a little more nimble urban handling. Around $5000 new.
This is a Round The World bike. A dutch gal that goes by "ItchyBoots" on Youtube has taken one of these through SE Asia and the Middle East. If you beat on it like a dirt bike then you'll likely break something (footpegs, mirrors, control levers, accessories like that). But the core of the bike is very solid.
And it's got some degree of that retro styling you seem to want.