Many say 420-430 is best for max power, some sat higer. I like '390'! Been as high as '503' and (I Think) it hurt it!! Alky runs 10-20* less than Gasoline. JMO
You should consider a forced water system - it'll keep it cool - probably around 300. ANyone who tells you you have to go hotter is a complete floof. You dont get speed from heat, you get speed from the right angle.