1978 318

No 318's had a single barrel carb but they did have a very small 2 barrel that looked like a single barrel at the top. You can find the casting number under the valve cover area. I should be either a 4027163 or 4027593 if they're 77-80 318 heads. 360 head casting #'s for 77-80 were 4027596 or 4071051. Note the common 318 heads I always saw were the ones that ended in 593 and the common 360 heads ended in 596.

BTW: I just noticed in my Mopar perf small block book it does say they used 4027596 and 4071051 (360 heads) in 81-83 high perf. 318's. Probably 4 barrell engines is my guess cause 360 ports were much larger and using a 318 intake on it would result in a big port window mismatch.