these are a great point of confusion for many...there is three types of heads and 5 types of inlet manifolds and not all will interchange with each other..
for ease of explanation i am not going to get into the finer points of 253/308 valves etc..kiss principal is what im workin on here..
first... we have pre pollution heads for HQ HJ and 2 inlet manifolds which are 2 barrel and 4 barrel.
second.. we have what i will call red pollution for HX HZ and 2 inlet manifolds which are 2 barrel and 4 barrel.
third...we have blue motor pollution heads for WB and only 1 inlet manifold for wb and that is 4 barrel..

include black v8 commodore motors in anything i have to say about blue motors...ok..;)
i am also not going to get into injected heads and harrop manifolds..

all these heads will fit any of the v8s..its the matching of manifolds to heads that gets confusing for the unknowing.
blue heads stand alone for interchange...you got blue heads then you have to use 4 barrel blue inlet manifold...
more to come with pictures later this week...