Honestly...how good was the 318...mpg / durability / hp

My favorite "318 story" is the mid 1930's Chrysler with a 318 that had a 4 barrel and headers.
Ran 14.10 every single pass at Kill-Kare in OH about 1987.
I saw that car put a 69 454 powered, tubbed chevelle with slicks on the trailer in the finals among other similar cars.
Heartwarming.
Lawdy. Talk about hurt feelins. lol