You chose the correct shocks for the car so they are undoubtedly doing their job to control the energy stored in the springs. I'd look elsewhere for the rattles. On one hand it can be a pain to systematically replace the rubber in the suspension of these older cars...on the other hand when you do, the car feels brand new. You may want to check and make sure all your exhaust hangers are OK; they are cheap and easy to replace.
'76 Moto Guzzi 850 Le Mans