"I was wondering if the others will fit or do they have different bolt spacing etc."

The bolt pattern is all the same, it's what's inside that is different.

You really get what you pay for.
That's why companies like Zenoah and Desert Aircraft pay the extra money for the better Carbs.

For a glow analogy. Cheap Carb = Super Tigre Good Carb. = OS.
The ST Carb. can be made to run good and you won't notice the difference until you put an OS Carb. on it.

By the way I don't run any of the expensive Carbs. But I'm pretty good at tuning them.
That is the Super Tigre mentality.