Engine noise at 40mph

[Bob from Northport]

We just began driving a customers' 1930 4Dr. after 2 years of body, interior and mechanical work. The customer advised that her father had the engine rebuilt a number of years ago, and what records we have indicate the engine sat for over 20 years.
It idles fine and starts great. At 30-35 it runs smooth and quiet. At about 40mph, there is a rattling noise in the engine that get louder as speed increases. I think it is piston pin rattle.


Any suggestions??

Thanks!!