Curt B.,
Did you ever determine what, if any, is the benefit for using the early Powergide intake valves? There must have been a reason why Chevrolet went back to 1-7/8" intake valves for the Corvette Six and all of the later 235 and 261 engines. It seems that only with a low-lift cam would there be much of an advantage for the larger valves with the siamesed-port flow path to the valves.
Hoyt
