I was there in the day and washed parts and pinned the rocker studs for many a short track SBC. Often the roller cam, lifters and valve springs were the only aftermarket internal parts. Still, having gotten used to aftermarket parts, I am continually amazed when I take apart a vintage race engine and see all those spindly stock SBC pieces in there. The Chevrolet engineers were tasked with building the lowest-priced OHV8 and given the directive to use as little iron, steel and aluminum as possible. When they were done, a ready-to-install engine cost Chevrolet about $55 to make. That it came to handle horsepower and RPM incredibly well was a happy accident.
We get used to seeing all the beefy aftermarket parts, but most are just for insurance and longevity. The stock parts would make horsepower for a while.
Speaking of round track, in the early days at Daytona, engine failures were the norm. Oils weren't that good and nobody knew about oil coolers. I've seen races where half the field dropped out with engine failures. None of the stock stuff was ready for 500 miles at full throttle and 6,000 RPMs. Pontiac was the first to figure out how to keep engines together around 1960 and they won most of the banked tracks.
Today, at 9,500 RPMS, failures are so rare, the whole engine program shop team would commit seppuku if they have an engine blow. But there's not a stock part anywhere on the car.
Studebaker-Packard V8 Limited