I did a intake test on a very mild 318. Factory '73 340 cast, Weiand Action Plus, Holley Street Dominator. All ran within 1 mph and 1.5 tenths of each other. The factory cast had the best mph & ET, even though it had the largest port mis-match to the 318 heads. 2nd was the Action Plus, even though lighter it ran 1 tenth behind the cast. Oddly enough, the Holley SD being a single plane actually gave the best 60 ft (barely), but the worst overall ET by 1.5 tenth and MPH was barely a click behind the others.
Bottom line is they all performed very close. Folks worrying about the mis-matched ports on a mild 318 are repeating what others posted or some other online gibberish without personally trying it.