Pat,
My engine is street driven, 9.50 to 1 compression mild cam no big revs with this motor, I am sure its a different story with a high rev race motor. I was told to pull a plug and ground it outside the block then gap it until i get the best looking spark, then close it slightly and that would be the best way. .040 sounds like a good starting point, there is also a real good webpage on reading your sparkplugs: http://www.4secondsflat.com/Spark_plug_reading.html
This will also help you with timing and fuel delivery setup.