I would design it with more movement than that, if you are going to use a motor, you are not going to have the inertia that you would by hand or pneumatics.I think the parts will still get the job done to move 90 degrees.
Even then, I wound up with a "sticky" mold and had to add tappers.
I just used what I had collecting dust. If you already have pneumatics/controls, might be less work to just use them.