Fork tube question


I need some help regarding the Busa forks. I'm an ex Busa owner and severely miss the bike, but anyway...

Does anyone know the diameter of the internal fork tubes? From what I understand the outer forks are 50mm, but I need the internal tube diameter. The lower tube that's attached to the foot. I'm not sure of the technical name.

I'd also like to know the length of the forks and tube as well, but if nobody knows, the diameter will be a start. Thanks for any help.
I don't know the dimensions off hand, but you can get the formal part names from the diagram below.

It looks like I was pretty close.  
Thanks, for the part fiche.

I need the dimensions of the part #1 or #2....both of which are the inner tube.  Mostly the diameter.