Lowering a GS is different from lowering a bike with conventional forks.
I'm making this up from the top of my head as I go, so FFS check this with an expert, but the geometry of a paralever rear and a telelever front makes the bike 'dip' rather than 'dive.....the whole body lowers itself to the ground but stays level rather than the front end diving, under hard braking. (It's like a curtsey rather than a bow, IYSWIM)
My logic tells me that you could lower the rear using your hyperpro 30mm shorter spring, then simply let the fork stanchions (which are little more than steering bars) slide up through the top yoke by 20 or more MM to keep the bike level in proportion when riding.......The fork stanchions slide up and down inside the telelever clamps so (again, I'm making this up with no experience of changing these aspects) the top and bottom yokes only hold the stanchions and the telelever front does the retracting/extending part....therefore (just looking at the diagram) if you just lift the stanchions up in the two yokes, it effectively lowers the front because the telelever and front spring are separate parts of the system.
If you lower the back end on a conventional bike, the front is effectively raked forwards which means the steering becomes slower, but on a GS, it's very different.
I hope an ex-spurt will come along and correct me if I have that very wrong, but if it was me, I'd go ahead and do it, then get my fattest buddy to sit on it and see what it looked like, then take it for a ride and just see what happens
