The 351w in my 4x4 has a offenhauser 360 manifold. I going to install a '66 mustang shelby supercharger on in when I reinstall it. The truck had pletty of torque but fell on it's face above 60mph. I can't seem to find the rpm range for this manifold. Would a Edelbrock performer be a better choice. I would like to optimize my power around 60-70mph which is about 2600-2800 rpm with 3.73 gears and 33inch tires. Any suggestions?

Brian