Why are 318's low HP and torque?

Mexican 318 was factory rated at 270hp
http://www.forabodiesonly.com/mopar/archive/index.php/t-14704.html

318's respond well to racing mods
this 318 with 4" bore 333 cube with 12:1 comp runs 9.1 @ 147mph in Sydney
If a 360 were used as the foundation with the same recipe of parts that would have been an 8 second dragster.