You would need both of the ports, because the one in the manifold must let the air in, and the other one vents it to the road. IMHO, I think the early 327's were the last ones with the road draft tube hole beside the distributor. It would require some serious machining to retrofit the 350 block, if it was possible at all.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!