I never heard of such a procedure...most everyone including myself gets the engine started and tuned to where it will run on the bench and then toss it in....after a good run check the plug condition...then make a needle change if nessesary...if its the gold head SS engine some use a temp gun to get to an optimal head temp much like the buggy guys..
If your running water cooled head I would recommend using the k&b fitting that reduces the water to the head..that will keep the head hot for a better fuel burn