In the '60s the smallblock, and later the bigblock Chevy was the standard installation for the majority of hot rods, and the reasons were many. Cost, reliability, power, and parts availability, drove this. That transfered to the drag strip. Unless you had the money, sponsorship, or ability to develop the engine yourself, then you could opt for more exotic or unusual parts.

Today being brand loyal to the body is becoming more popular, and the Chevy is frowned on by many, due to it's long term use. Maybe it has become to generic for some... but if you were building in those days, most would choose the engine that everyone else was going fast with, and doing it reliably.