Why bother? Changing the geometry of the valve train creates far more problems than advantages, and few engine builders have the engineering ability to do it properly. It would be necessary to change the position of the rocker shaft to do it correctly on a stovebolt engine, and the machining costs would be horrendous.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!