Back on topic,

Try a little more speed,

When I first started driving my truck ('53 with '49 216 and three speed), I wouldn't go any faster than 45 mph because I thought it was going to fly apart. Then one day I was forced to pass someone that was going even slower than me, and I found that when you exceed 45mph and get up to 55 it smoothes right out.

Try using a gps to establish your actuall speed. Depending on your tire size, you might be going faster than you think (or slower).

Turn it down a bit,

When I first started driving my truck it was deafening. I wore ear plugs. But people would always tell me my truck was so quiet. That's when I realized the cab was picking up all the engine noise and amplifying it.

Change out your cab mount rubber pads and the rubber motor mount parts. Do what you can to prevent the engine vibrations from transfering to the cab. Also insulate the cab and fix leaky exhaust to prevent engine noise from radiating into the cab metal.

If you "turn the volume down" you'll get a better idea how she's running.

Vintage Car Artist