Those are '75-'76 smog motor heads..you deffinately DON'T want to be running a single plane intake,your best bet is a performer intake it has the small ports for 318 heads,the performer rpm is designed for 340-360 ports..For comparison a buddy of mine is running a '77 smog motor 318 with nothing more then a performer intake,carter carb,comp cams .477/.480 cam,and a 8 3/4 w/3.91's,his best time to date is a 14.9...