Conradcliff, the reason for your second calculator's error is because you only have THREE teeth on the clutch sprocket.
FWIW, follow the general consensus here, but research where the Titan engine's max torque and hp range is. Then gear for that.
In quarter-mile racing, they recommend that you overgear slightly at the top end. However, since you are sustaining this top end speed, ya don't want to overgear.