Thanks for taking the measurements. I measure my Mikunis at 120mm, my isolators at 19mm, and my manifold at 136mm. Adding it all up, I think my combo ends up being about 10mm longer than what you have.
Of course, I have many hours of porting work in the manifold... and these isolators supposedly do a much better job keeping the carbs from vibrating and functioning improperly...
But, the box won't fit as is. Specifically, if it were already assembled when put in the car, I think it would clear... But, you can't put it on the car already assembled.
I could put plugs in where the bleed screws are and just bleed the system elsewhere. They are more of a convenience than a necessity. Figuring I could pick up half their length, that gives me 8mm, with 8mm left until interference with the brake master cylinder reservoirs.
It looks like Sylv has more than 10mm air gap to his brake master cylinder. How much room do you measure from the air box to your master cylinder? And how much do you have to pull the box cover out before you can lift it free of the back plate?
Finally, the box looks like it tapers from front to back. I measure 113 mm from the face of the front carburetor to the shock tower face. If that isn't enough (also allowing for the removal of the cover), I'll have to give up on creative thinking and just change out the manifold or the isolators. Sorry to drag this topic along so long.
Garrett