Most 318 heads port out pretty decent for a small displacement.
Charlie Servedio got some pretty good numbers for the small port head. Out of the MI-318 closed chambered head (IIRC it’s closed chambered) he found 231 cfm with the stock 1.78/1.50 valves.
CFM X’s 2 = possible potential HP = 462 possible HP.
The still smaller than a 340/360 head port equals higher velocity for a more efficient port. I guess it’s no wonder MoPar sold the ported 302 castings in the catalog boosting a 55hp gain over 360 heads.