Why are 318's low HP and torque?

my duster was a six car, i bought a sweet little 67 318 / 727 for 400 bucks off CL and with less than 400 bucks and about 8 hours, pulled the six and had it running, just because i love V8s. this way i can have the V8 and pump my money into a 360 for it on the side. this was done on the cheap cheap and its still getn the job done. its not the fastest car on the block, but it sure is fun and kinda purty doing it. just another thought to consider :D