DSLR Tilt Shift Medium Format Lens

So I bought a Bronica Zenzanon 75mm f/2.8 medium format lens to use as a tilt shift lens on my Nikon D90 but I barely have any clearance between the back of the lens and my camera body. I thought the flange / register distance was supposed to be much larger? I have to have the lens back about a 1 cm from the camera body to get infinity focus; what gives?

http://www.keithloh.com/drupal/diy_tilt_shift_lens_no_exciting_pictures_yet

It's almost exactly like that pictured lens and he's fitting bellows between his body and lens.
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-Paul