My take is that break-in of engines from decades ago is solid. Heat cycles and moderate engine speeds are good to keep spot temperatures down until surface friction is reduced by the break-in process. My own experience has convinced me long ago that varying RPM's does help seat rings better. A corvette engine has the advantage of a modern cooling system, high pressure oiling, speed limits and gearing that won't strain engine parts, and especially the advantage of modern metallurgy that older engines do not. There is a huge difference between the life-span of modern crankshafts vs those made even during the fifties and sixties.
edit:
Regarding ring seating; the varying cylinder pressures associated with increased throttle and decreased throttle (esp under load) help the rings seat. Whenever I rebuild one of my bikes, the first thing I do is get riding in the hills. This is true for four-strokes but especially true for two-stroke engines which I have rebuilt countless times.
The cylinder honing process used today in new modern engines is a far cry from the old days..
Here's an article which explains plateau honing...
https://www.productionmachining.com/...cation-control