Wondered about that statement too. Our 54 Ford V8 had OHV.
I wonder if the OP really has a 1964 instead of a 1954 Jeep. This would explain the Tornado engine. In 1964, all U.S. cars were 12 volt. In 1954, only the GM Oldsmobile, Buick and Cadillac were 12 volt. The Tornado is neither a 6 volt nor a 12 volt engine. The engine is not related to the electrical system.
Kaiser Jeep Willey’s Tornado straight six…
Overhead cam, not overhead valve. With an overhead valve engine, the cam is still in the block and operates the valves with lifters,pushrods and rocker arms. V8s by Cadillac, Oldsmobile, Chrysler,Studebaker, DeSoto, Dodge and Buick all had overhead valves before your Ford.