Look at the diagram you sent! The radius of the grind is determined by 1 thing. R1 distance , because the rocker is fixed to rotate in the same axis as it does when assembled on the rocker shaft..! The variable is "HOW MUCH" you grind. Entirely up to the operator. But , the outcome or radius will be the same. The diagram that you sent also makes it clear that it is not that critical what the radius is as long as it is not flat and the area of contact is approximately the same. Furthermore, I believe if you look at the geometry of the whole assembly, you will realize that the area of contact is likely also influanced by the cam lift.
