NAPA does carry voltage reducers. It was pretty cheap - I bought 4 things, including the voltage reducer, for a total of $16.
I put it on my '54 (running a 12 volt system) and my gas gauge is operating normally. The only thing I didn't like about it, is that it is made to be mounted (it is too heavy to hang off the back of the gas gauge). I had to be a little creative with mounting the voltage reducer behind the dash. Wasn't hard, just had to plan ahead. FYI.
Good luck,
K
