I thought in the vintage races, you could run about anything you wanted to. Am I mistaken?
It depends on the club hosting the event—and there are many vintage clubs. The clubs who are most-strict won't allow you to modify a factory-stock car to be competitive for its own sake. Some clubs will accept your car if your car has competed historically in actual sanctioned racecar events. Documentation is really important.
"...Not to bust anybody’s bubble but that is not a 426 Hemi. This car is an old Trans Am car..."
Beats me which is which from the video, but the sound is V-8, fer sure.
I've spent some time instructing on the track in similar conditions, but in PBOC events.
My '91 4-cylinder, 16-valve, BMW Q-ship does lose in the straights against the latest Corvettes, but most V-8 and V-10 drivers don't use their brakes to best advantage on the track. Therefore, depending on where the finish line is located...WRT the final curve...it's possible to out-brake—then out-corner bigger-engined cars to cross the finish line first.
Anyway, "winning" isn't so important in the practice sessions.
At 4:10 and 4:20 in this video, the Ferrari driver may be signaling the bigger car to pass.
That's what I would do if I had a valuable (and hyper-documented) Ferrari in a vintage PRACTICE event.
I carry that experience to my daily driving: You'll never see me being followed by a gasoline, propane, or cement truck!
==8ºO