Reverse Manual Valve Body

I have a CRT reverse pattern valve body laying around and a low horsepower car with a relatively stock 727, was rebuilt with performance frictions and a bolt in sprag, but that's about it. Just wondering what sort of 1/4 mile improvement I might see with a valve body change? Currently running 14.1 over the 1/4, has 4.10 gears and is not street driven.