erm...........
That is near impossible to answer.
Cylinder head specialists only really specialise in a few heads, or a marque. It takes lots of time to develop and continue developing a head, its not a matter of someone just being a good flow specialist, it takes time, testing and more time, lots of thought and sparks of eureka.
Someone who is s**t hot at a cosworth head will be almost usless on a honda because they follow entirely different port design theory.
However most great head people will be able to make any head flow better, but like i said, alot of the specialists make heads which would convince me to stick with std items.