Well, a buddy of mine got two sets of Road King air shocks last winter. He put one set on his Sportster and they fit perfectly. He gave me the other set since one of the shocks on my California had developed a leak.
Length wise, the fit was great. The issue was that the eyes on the shocks were half inch (12.7mm) while the studs on the Guzzi are 10mm. Also, the eyes are about 3/16 inch wider than the studs are long. So, not an easy retrofit, but it can be done. Having a metal lathe in my garage helped a lot.