detonation can be in many forms, it doesnt always have to pepper the pistons with dents on top, it may be as discreet as looking like the piston has been beadblasted on edges. It can simply wreck the rings(looks like water spots on them), break off the intake skirts, audibly ping, wipe out crank bearings. If you broke the skirts then you had some form of detonation. The pistons were rocking back and forth violently, at the wrong time to break those off.
It all depends on the actual head set up, squish angle and radius being the most important element to preventing detonation on a lower octane fuel while running fairly high compression ratio's. Over advanced timing can also play a large factor. Just because they were mega power heads doesnt change anything, I recut those domes all the time.