webers are italian (some made in spain) and solex's are made in Germany.
Unless solex is a model name, in which case I have never heard of it.
In any event, the carb looks similar to the 2 barrel solex carbs they used on BMW's in the late 70's early 80's. The base on the solex was always the same as the weber, it was like the german DIN measurement or EAI standard wire coding for stereos, a standard that made sense and so everyone adopted it. SO it wil use the standard weber adapters.
It doesnt look like any weber design I am familiar with either,
I dunno, the best upgrade for a solex was/is a weber.... Looks like a great crab for mazdas though, 34/34 is a good size. I say since it is all brand new and warranted its still eons better than a stock Nikki carb. Give it a shot!