Bearcat "The Pontiac did not have the exhaust scalloped out like the heads in the picture. The Pontiac 427 is a spread port head not a symmetrical head. The spread port does not mean that all of the runners are spread, it means that the pairs of rockers are spread apart. If you sit a Dart intake on the Pontiac heads the front pair of runners would line up good but the intake would like about 1 1/2" to reach the rear pair of runners. Slide the intake to the rear and then they would line up. Edelbrock was the only ones to ever make a cast intake to fit the Pontiac pro stock head and only made a few of them. I don't mean to be a a-hole here but I have used many sets of the 427 and 3386 Pontiac heads on engines not just seen some here and there. I you want the true facts call Brodix, they can fill you in on the facts because they were the original manufacturer of the first casted rolled spread port Pontiac heads. Don't mix up the Dart Big Chief and the Brodix Big Duke heads as Pontiac heads, they are 18, 16, 14 and 12 deg heads and are not like the original Pontiac heads. The heads do not have interchangeable parts."
I'm not trying to be an A-Hole here either, but, I think some of the comments are a little misleading.
I have two cast intake manifolds for the GM Pontiac 427 heads, that are not made by Edlebrock. They are both blower manifolds that were sold by Street and Performance. One of them I bought brand new in 1987 for the new set of heads I bouight from GM in 1986. I have four sets of these heads now, two of which on on running engines. The first set are a blown 572 deal, the second is an injected 500 deal.
Two of the sets , not on engines, are the "scalloped" style that are shown in the above pic ? These were the later style castings from what I've seen, that when they scalloped them, they also added the tapped holes for the steam pocket lines.
I think what you see in the above picture is a GM Pontiac head that has a modified Dart intake, possibly to match a pair of modified intake port heads. I've see heads that had the ports moved more towards the "semetrical" style and then the move the ports in the Dart "Big Chief" intake to match. EPD was the one that did this more than other guys.
The one set I have has had the Dart "Big Chief" bolt pattern drilled and tapped in them.