Jim,
Any flat tappet camshaft run-in involves immediate startup, no mucking around to fire up etc.
Timing light to be fitted, and timing to be verified at around 30 degrees by a second person at startup. Lock distributor.
So the engine needs to start first go, and run at 2000 rpm plus,
oil pressure verified and checked during the procedure.
Run engine at 2000 - 2500 varied in this speed range, do not idle, do not blip the throttle. Engine needs to run for 15 - 20 minutes.
Monitor engine
oil pressure, engine coolant temp, and engine sound.
Timing can then be checked at 2500, and then at final hot idle speed.
Gary