I am assuming by height adjustable, you are referring to spring preload and not actual ride height?
If that is the case, the Hawk rear shock has a bit of an odd-ball bolt spacing around 320mm center to center on the eyelets of the mounting bolt holes. That means there aren't really any off the shelf options. I have found many similar to these
https://www.aliexpress.com/item/KEOG...460.0.0.bw5pDR
The 310 or 325mm unit would work with a minimal change in ride height to the bike. The 325mm one would raise it an amount you wouldn't really notice, and the 310 would lower the bike less than half an inch. The issue with these shocks is that the ends are not the right width for the mounting tabs, so they would require spacers - especially on the swing arm end - to operate correctly. Also, there is no speaking as to the durabilty/quality of these shocks. They may be fine, but you never know.
Your next option would be a stock TT250 rear shock. Since the TT250 is more or less the same basic bike as the Hawk, it's rear shock is more or less the same, but offers spring preload adjustment. The downside is that it is $187, but the upside is that it will bolt up. It's only about $75-80 more than the first shocks I linked, and are proven (and much less hassle)
http://www.cscmotorcycles.com/TT250-...p/zt27-101.htm
Third option is to have YSS Custom build a Z302TR rear monoshock for you. This will get a rear shock suited to your bike, specs, etc. Has spring preload as well as 60 position rebound dampening adjustment. I am considering this option, but the downside is the cost at $279.
Obviously, there are other options out there, but many people are happy with the stock Hawk unit