oh wow - been there done that !!
first of all, please tell us what the carb goes to.
year, model, and P/N of the carb body itself.
and - how much does a replacement carb cost ?
Option:
in
my world, I would find a piece of soft aluminum the thickness of the black plastic bracket ........
you could build a duplicate with minimum tools, a little skill and a lot of time.
(plus, you would gain the self satisfaction knowing that
YOU fixed it yourself - from scratch).
and yes, you could use plexiglass or other plastic . . . but, it may just break again.
In my past experience, I have had zero success with adhesives and epoxies on that type of plastic.
the "rub" would be getting the black bracket off in one piece and figure out how
to install the new aluminum replacement and keep it from falling off.
For instance: when you grind off the flat head that holds it on, you need
to find a small tap and thread the inside to like a #4 or 6 size screw to hold it secure.
-or- maybe drill it out completely and run the holding screw all the way through the body.
IF you decide to go that route, be careful not to cause more damage to it
so that you can glue it back together and use it as a template for the new one.
Even if you DO find a replacement bracket, you have to go through the process of
getting the old one off and the new one securely on.
but
in the meantime, keep looking for a donor carb with some usable parts.
stroll on over to https://www.aomci.org and post the same issue in the "ask a member" section.
tons of good information, ideas and very talented people there !!!
good luck - let us know how it goes.
.