I looked last night.

It is the air intake for the IAC. From in front of the Throttle plate and behind the maf. Then the IAC allows this air to bypass the TB plate.

Reason behind my asking is 67Goat used that instead of the lower plug to tap pcv in. It'll work from what I can see. Only thing I'd be leary of is that PCV oil is going to coat the IAC, which usually gets dirty enough on it's own.