Those blocks won't move once tightened in place if they are like some I've seen. One end fits inside the stock mount on the swing arm, the other is wide enough so the shock blots into it.
The one end is made to fit agaisnt the swing arm so it can't rock up if thw wheel comes off the ground.
Using these work to help short legged people reach the ground. Same as shoter shocks. Some just like the new angle of the shock.
This makes the angle look more like the Specials shock angle. If I wanted that shock angle I would just get a Special, Oh wait a minute I have a Special. Well actaually two, one road ready, the other needs carb work.
I have a highly modded 75 though so I have both angles.
The 75 gives slightly better handling than the Specials. The 75 has a 130/16 on the rear, Easiest way to get rear disc brake. The Specials have lower bars so the differences are note as noticable.
Leo