HOLD ON THERE JOHNNY!
Edelbrock heads are considered closed chambered heads. 65 & 63cc's. The 63cc head being the popular model. 65cc head for OE pistoned 340's with positive deck heights.
An example of an open chambered head is an X,O, etc letter heads, most every 360/340 head I ever crossed is an open chambered head. I'll re check my 308's, though I think there open.
W2's are a open chambered 70/72cc head chamber. Not all of them though. Some were as small as 65cc, 55cc & 47cc. I do not know of another aftermarket head that is considered an open chamber. Except the W2 70/72cc models. (Most popular by the way.)
The W5, 7, 8, 9 all had chambers ranging from 63 down to 51.
Since it is stated via the manufacture company of the create short block that it must use an open chambered head, this leaves any decent performance head OUT in the cold.
While we do have a few here that use a OE head on top of a 400+ cube engine, IMO, I can't see why and think no one in there right mind would use one. Except for towing? In all fairness to the OE head, it will port out right fine, just sadly short to allow the 408 to shine.
As I mentioned earlier, knowing what slug is used, where it sits in the cylinder (how far down in the hole or not) and the dome amount and height is a need to know issue.
