Military-surplus 270's were popular with the dirt track racers my Dad ran with in the late 1940's and early 1950's. We ran well-modified flathead Ford V-8's on alcohol, and didn't have a lot of problems outrunning the 6-cylinders, but if the GMC's ever got hooked up well and avoided getting a lot of wheelspin off the turns, they could almost run with us. The 302's didn't come along until somewhat later. Their main advantage was more torque from the same external-size engine as the smaller-displacement GMC's.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!