Centrifugal advance are available for cam timing sprockets. But are more complicated, certainly above my skill level.

I had and adjustable cam timing sprocket on m VW Scirocco and Audi Coupe. The amount you can shift your motors torque band around is nearly unreal. Could take my VW from tractor like low rpm torque to high reving race motor feel. I bought one, and my friend made a copy.

Not intended as a real how to guide .... But if you have a spare sprocket, drill press and a lathe. It is pretty easy to make. On the lathe true up the inside of the sprocket, square corners are best. Make an aluminum plate to fit the center. Drill and tap the outside circumference, do the same on the spoke area of the sprocket. With a degree wheel mark off + and - 2 or 3 degrees, I can't remember now how many degrees now. Slot outside holes in the plate apropriately. Cut the spokes in the sprocket.