You could consider custom-bending your own. Way back in the 80's when I was 17-18 years old I had a classic car as my first car. Back then there weren't the suspension companies there are now, and it was impossible to get a stout sway bar to fit my mid-size car application. I had a lot of tools at my disposal; I took a torsion bar (Torsion bar ...not, anti-sway bar), out of a full-sized GM car (Toronado), which were 1 1/8" diameter and pretty long, long enough for what I wanted to do. I heated er up and bent it accordingly to fit one bend at a time. After each bend I quenched the bend area in oil. I did an initial dip, removed for no more than a couple seconds, then diped/soaked it till cool. This was per a friend of the family at the time who worked at a foundry (I'm sure there are youtube videos on best quenching techniques). Then drilled the ends to suit. It performed flawlessly and never lost it's shape or form. Then I took the existing 5/8" sway bar (that was originally on the front of the car), made a few mods and installed it on the rear of the same car. Add some cast aluminum wheels, slightly heavier duty springs, and let me tell you, I had the best canyon-carving early 60's car in the COUNTY!!
I also did the same thing for another vehicle I bought a few years later that had the typical 60's terrible suspension. Again, never lost shape or rigidity, cornered flat as could be. GM trucks use torsion bars, should be plentiful. But might not be thick enough for what you want to do. Unless you can find one out of a HD or 3/4 ton/Dually (do they use torsion bars?).
I bet a guy can probably buy the right length and thickness sway bar stock (solid or hollow) from some of these sway bar companies and custom-make your own. Or, if you bent what you needed in, say, 3/4 or 1" EMT conduit or black pipe ...bend it up so it fits your custom H3 front suspension ....then send it to a sway bar company, you can probably work with them to duplicate the shape for you in whatever thickness you need (they can probably do the calcs and suggest a thickness). Or I wonder if it's possible to modify your H3's existing anti-sway bar?
Another option, if you off-road a lot and don't mind spending a few bucks, is to consider a remote anti-sway unlock/lock system like the Rubicon and Gladiator use (the Bronco will use one too they say). I forget the company name who makes them, but just do a google search. Should be able to come up with something.
Anyway, don't give up. Those are some ideas for ya....
Good luck.