What makes the A series 318 not at all a hot rod engine?

1965 dodge coronet 318poly (rocker covers wavy on bottom) torqueflite auto, my mom drove it, my sister drove it, passed it to my daughter who drove it till the unibody folded in half. 1989 I picked up a 1940 Plymouth pu, bad shape but a project. Used the engine tranny rear end and wiring harness from the coronet and a 1978 pinto rack & pinion front end. 2010 I started working on it again.

318 locked up. Marvel mystry oil and wd 40 in the cylinders and a breaker bar, trying every nite to move it, about a month and I got it to turn 1 complete turn. Took the rocker covers off to make sure

all valves were moving, it started and now I have about 3000 miles on it. It needs valve seals and a rear main seal but runs great all stock with the 2 barrel carb. I've always been impressed with the gas milage and don't plan on hot rodding it when I over haul it when it needs it but as fast as it seems to be now I'm curious as to what makes it , not at all a hot rod engine, as was stated in anotherredman's answer to my last question about the 318. The answer he gave me was very informative. But I am curious about the hot rod part.