318 build #2 "cost minded" for the '74 Duster

well for context. My hot mild 360 with a 4 barrel, headers, very tame ported heads, a wide ratio transmission and 3.23 gears went 18 seconds in the 1/4 on good tires so there's my proof/reasoning it wont go 13.9s in a 1/4. I had more cubes, a good carb, better exhaust system, ported heads, and steeper road gears than yours and it did that time. A 318 of lesser value will not be faster under any circumstances UNLESS you are spraying/boosting it.
1968 dart 225 slant six 145 gross hp 2930 lbs without driver goes 18 flat stock
at 3100 a 360 4spd 3.23 with traction should run 14.5 backwards
did he tun it off at a 1000 feet?