318 4 bbl intake..??

Unfortunately, there is no "right" 318 4bbl intake because 318's didn't get a 4bbl intake from the factory until somewhere around 1980. Most, if not all OEM small block 4bbl intakes will have ports a little bigger than a 318 head. Will hurt air flow a bit, but it's been done before. Not sure if that continued through the end of carburated 318's. Later 360 heads do not have a letter designation, so you have to find the casting number either on a port under the valve cover or on the underside of the head under the intake. Thermoquads began being used on small blocks in 1972 and I believe at some point, in the '80's, they actually used a Quadrajet.