I bought a Park Tool TW-2 Torque Wrench 3/8- Inch Drive from Amazon.com. Then found a set of Craftsman step-up and step-down adapters on sale.

 

As long as it's just surface rust, the beam style will still be accurate.

One quick note, for general use I only have the inch/lb 3/8 drive. I found when I tighten axles I end up at about 40-45 ft/lb using the one breaker bar I have. So I don't bother. If I'm doing an engine head or the like I'm using either the inch/lb if it applies or I get my father's ancient beam style Craftsman ft/lb 1/2 drive.