When I get home I'll take a photo of the mods to the low speed mixture needle. As to the initial setting for the mK x carb there is no such thing. Duke had no idea as to the fuel you were going t use, the tank placement or the weather conditions.
Duke does say to set the needle detents circular disk on the needles with in 1/16 of an inch of the to the tips of the needle retention clips. I just prime, turn and burn!

I have to say I'm a little surprised at how few folks know how to fine tune a twin needle carb. This isn't just a Fox issue but any true twin needle carb. Again, this is not unique to Fox,

All the best,
Konrad