Jeff ,
I take it you are suggesting a single depression?
Yes. Tried to find the pictures that were posted for the discussion (pre-crash) of the shape of the depression but can't locate them at the moment. But looking at allot of what appear to be unrestored Mustangs built at the same plant and time I'm seeing allot of single depression examples which is making them hard to ignore. Of course allot of the period pictures don't show the surface very clearly but many appear to lack a second on also but due to condition of the pictures they can't be used by themselves to any certainty IMHO
So since they were all installed (both Hipo and standard V8 air cleaners) at the same station at San Jose it doesn't make sense that the worker had two separate bins for each. More likely one for V8's and one for 6 cylinders
Just bringing it back up for discussion