Well I can tell you that John will ask you why are you staying with B's when staying N/A. I think for auto crossing where you keep the rpms high and try to stretch out the gears as much as possible I'd say a BB aluminum 4.6. That way the nose of the car will be ligher and depending on the cams selection and valvetrain you could easily spin 8000-8500rpms. Just make sure you have an adequate oil system. Maybe an external pump. I thought of going for a max effort N/A B headed 5.4 but after researching pricing its a lot and I'd only make about 400-420rwhp. I can get that with base vortech/novi kit. Plus max effort n/a motor is not fun on the street. Good luck with your build. -Mark