Mike,
OEM Chevy head had three straight intake ports.
Rich, it is my understanding that the Howard GMC head was designed by Howard Johansen using the Chevy angled ports. Not a use of the Wayne patterns.
Funny story from Nick Arias, he claims that a few years after Wayne Horning and my father split he asked Horning why didn't he design his GMC head with angled ports. Wayne's answer "too stupid".
DW