If having the contact pattern on the valve tip near center is important, I'm curious why AFR didn't simply relocate the rocker studs away from the valves so a variety of commercially available rockers could be used.
I'm still very much a student and learning on this whole valve train geometry topic, but I'm going to attempt to give you an answer to your question based on the understanding that I've gained so far, (if I'm wrong then I'm sure that someone will correct me): I'm not so sure there can actually be an ideal rocker arm stud hole location that would allow most any standard roller rockerarm to be used. The reason for that is due to the fact that the rocker arm stud angle converges with the angle of the valve, so the longer the valve stem is, and the taller the installed height of the valve spring is, the closer it brings the rockerarm to the valve stem.
In a recent conversation I had with engine builder Mike Lewis, he mentioned to me that there isn't really any such thing as standard nor long valves anymore, due to the fact that there are so many valve length options these days. If I may add to his thought on that, I'd also say that there is also a plethora of cam lobe options, offering the end user from .450" total lift at the valves, to close to .900" lift, (with the majority being from .500" to .775" lift). The point being that there are so many possible valve train combinations and so many variables, that it's probably impossible for any head manufacture to locate the rocker stud holes in a place that would make it possible for most rockerarms to be used by most of their customers. The more valve length you use, and the taller you go with the installed spring height, (in order to avoid coil bind when using high lift camshafts) the higher your rocker arm ends up resting on the rocker stud, and in turn the closer it gets to the valve stem.
Remember, the angles of the rocker studs and of the valves converge with eachother. The two angles are slanted towards eachother. Therefore, there is really no way that a cylinder head manufacture can re-locate the rocker stud holes to a place that would serve as a cure-all for any possible combination of cam lift, valve length, and valve spring installed height.