Theres a guy over on the east coast(Steve Clukey) that uses a sb n/a combo using an X block. Not sure the stroke, but spins that thing to 8000-8500rpm on shifts. Its in a duster and has been in the high 8's. Very impressive sb.

http://www.youtube.com/watch?v=aIxaesJ190U

http://youtu.be/lCZAaN7fFLg