Here is something simple that may help you?
The Holley carb is threaded 1/4"-20. If you use a 1/4" coupling nut, use a short piece of 1/4"-20 threaded rod to attach it to the carb and then use a 1/4" bolt on top through the air cleaner base mounting bracket, it will probably hold the base tight enough to stop it from rotating without bending and distorting the base bracket?
Here is a picture of what I am talking about on my secondary carb. You can see the coupling nut sitting under the retaining bracket.
The nut is going to be about 7/8" long out of the package so you can either cut it to length or stack two to get the right height.