ttt also will incluse the original 289 heads if you would rather have a regular 289, all you woul dneed would be a set of pushrods, head gaskets, and intake
but the clevor will definetly make more power.
its a sweet little street engine, somthing different-you dont see every day.
i had an engine similar, with the same heads and close cam and it ran 13.5 with an automatic and drag radials.
so with a 5 speed, and 4.10 gears mid-low 13's should be no problem