do I really want to rebuild the nailhead or just drop in a chevy crate motor.
are you going to be spending a lot of time at the drag strip? then a big Chevy crate will be cheaper and give better performance.
are you mostly going to be cruising and showing? sorry, an SBC doesn't look even half as cool as a dressed Nail. and with all of it's torque, a Nail will give excellent results for stoplight racing.