Why a Reverse Valve Body?

I recently bought a bunch of stuff from a guy for my drag car, a '70 Dart which will have a 440 and 727. Included with the parts was a Cheetah manual reverse valve body. The instructions dont mention band apply in 1st, but do say 1st gear, no engine compression braking. Does this mean no band apply in 1st? If not, how can I modify it to apply?