I use engine symulations that take a lot of guesswork out of planning your build. Comp Cams has a free download. If you wish, I could send you a copy of my 'Dyno' This program is great, with loads of variable parameters, including cam files, head mods, bore/stroke configurations, juice, induction boost or normally aspirated and much more to build your own model,,, tuffnuff2@yahoo.ca