The 427 W I had was broken in very easy for about 1000 miles with easy warm up and varied lower RPM. The 10-30
oil was changed about every 500 to 1000 miles and proper octane fuel was used. Maybe overkill, but what's a few extra bucks for the fuel and the
oil chang every couple months? After break in the warm up always included engine warm up temperature and the
oil pressure drop before any spirited driving. The transmission is recommended to remain lower RPM and varied RPM by Tremec as well for 500 miles. The result was an engine that didn't smoke and ended up being one of the quickest street 427W ever put into a Superformance.
You can read about some other results of what happens when cars are pushed cold with new engines after people put then on dynos right away and/or take little care for break in. Generally improper fuel and general poor warm up procedures go along after the poor break in too. Just search some of the lengthy threads about the manufacturer warranty and how unsatisfied the people are with their engines.
Funny story too. My friend just bought a new Audi R8. The dealer told him the car is ready to run hard right away right off the lot. That's typical. We flipped to the break in procedure in the manual that came with the car. Guess what? Varied RPM, lower RPM, 1000 miles.