Corrected is for the altitude, barometric pressure, air temp, and it will correct the HP level according. Say the corrected altitude is 3,600' out side it will adjust the power level to sea level or so.
I looked up Joe Gibbs oil and it is 30w or better/thicker. Ask your engine builder what the main and rod tolerance is, and if you can run 10w30 racing oil of some sort. I run 10w30 Valvoline racing conventional oil in my small block. Everyone has their own idea of whats best, but synthetic is really not necessary in a track engine. Run a Wix filter #1068. just my 2 cents.