I just hand a thought regarding VA's. I understand about production tolerances and compound errors causing some valves to be way out of line with the bores. But peep this: There are 4 ports to each valve: UP-IN, UP-OUT, DOWN-IN, and DOWN-OUT, I'll call them. Sure, a skilled craftsman can shim the valves to be precisely aligned with ONE of the IN or OUT ports on both the UP and the DOWN stroke. But if either the valve or valve casing is not perfect, then even though the UP-IN is aligned, there is no guarantee that UP-OUT is too. And if it's not, then I really don't see a practical way of getting them both aligned together. It's sort of like a relationship between a man and a woman (or m/m, w/w, or whatever, if that's your thing...) As long as they are both independently healthy, happy people, they can probably figure out a way to mesh. But if either one of them has serious personal "issues" and is so far out of whack on their own, then no amount of adjustment by the other is going to greatly improve the relationship. Just my thoughts.