Its just not practical to try to make a "one size fits all" carb that is why perry has this whole range.
Best is to find out what the most likely engine is that people want to convert and start with that one.
And a carb body that has the holes for the os style screws will also fit a clamp style engine with the same hole size so there will be some overlap.

Also rembered this part https://www.justengines.co.uk/shop/c...v=d2cb7bbc0d23
it might be usefull for people who want a seperate solnoid setup.
I got 2 to repair a 20 fp carb