The 6V I was referring to were the carbs.   I ran a three two barrel manifold (Edelbrock I think) on my 312.  I believe the carbs were little Carters.  It looked great and ran well, but to be truthful a 600 Holley ran just as good without the hassles.  I will definitely switch my 55 T Bird over to 12 volts.  I'm a Holley guy, so that's probably what I will run.   I'm looking for an iron 312 Holley pattern intake right now.