The big thing with break in is getting a lot of timing into the engine when running. Retarded ignition timing drives exhaust temps WAY up. Get engine to 2000-2500 and put 34-38 degrees of timing in it right away. Have the distributor snug enough that it won't turn, but, loose enough that you can twist it. You aren't going to hurt it, even with 40* of timing, as it has no load.
Additionally, initial fire up creates more frictional heat than something that has run for even 1000 miles.
I use two large box fans on high in front of the car to keep air flow moving at a brisk pace.