Brilliant work!
This is such an exciting project - it'e double the focal lenghth of Zane's
http://www.sdmtelescopes.com.au/SDM007.html and with a 4000+ mm focal length is going to be the ultimate high power scope!
It would be great to get them side by side when they are finished and do a compare and contrast - they are at opposite poles of the monster dob scale! Chuck in a standard 25" F5 as the control by which they are measured.
BTW, If the eyepiece height is low enough to avoid a ladder you may be able to angle the focuser like smaller dobs to make it more comfortable at lower declinations.