Way back when Verlicchi made the frames, and the Harris brothers made a number of the variant sold through Sports m/c's, the true geometry was much as in the picture. If Steve Harris states 295mm for the shock length then I am sure that's what they used (in the good old days). However, with the passage of time and in our minds eye due to current trends we expect a slightly more radical approach to seat height/fork angle etc. Maybe that's why a TT2 using the old set-up appears more like a cruiser than a TT2.
A general indicator of ride height is to look at the footrest position. If the frame is either Verlicchi or a copy using the same geometry, as with the Harris, the underside of the footrest is generally in line with the top of the swing arm tube, as it is in the pic here.
Using a 295mm shock together with front forks as per the original length at 580mm results in what we can see before us.
Having said all that, non of the above has any relavance to anything but the past. Fast forward 30 years where we enjoy the benefit of modern tyre technology, way better suspension, and an elbows and knees riding stlye that has changed even more so. The geometry simply evolved to accomodate it.
Have a look a the side on pic on this link to see what I mean about the old TT2 geometry.
http://www.ducati-tt.de/12Bilder_worksr ... ads_14.jpg