Just found this,
On u tube "360 magnum head porting
(Intake ports) "
The guy worked a set of stock replacement magnum heads from Jegs to 259 CFM with a competition valve job only, before he started porting them !!
Worth a look
And this is how it begins ...misinformation...with somebody whose eyes do not know what they're looking at.
That head has chamber work all around the intake valve and has the guides mildly profiled in a subtle way that narrowed them up not made them round and aerodynamic... AKA if you only recognize porting as to look a certain way.. you wouldn't know what you were looking at. Nothing personal Brooks.. but if I don't slam the hammer...it goes on as fact when it is indeed a mistake.
They also backcut the valves. I don't backcut. I've seen a tendency of reversion on Street stuff with big cams and when I stopped doing it that went away