I just got back, Steve, and reunited with my '48. I have another video w/sound taken from inside the cab.

Sound from Inside Cab.

I've received good suggestions (above and other friends). I've already looked at some of them and gave the results above. I'll look at others in order of how easy the checking would be.
I will:

1. pull the valve cover and idle up the engine. The sound begins at 1300 RPM. Using a stethoscope, the sound is much louder on top of the crankcase vent tube than the valve cover but this only costs one gasket.
2. pull the harmonic balancer. Check it out and run the engine up to the 1300 RPM.
3. remove the timing gear cover and check for rubbing marks. I understand the timing gear can get a bit catywompous and rub on the cover if I understood correctly.
4. get back in touch with you guys!

Thanks for your help so far and into the future!

1948 3/4-Ton 5-Window Flatbed Chevrolet

34 Years. Now with a '61 261, 848 head, Rochester Monojet carb, SM420 4-speed, 4.10 rear, dual reservoir MC, Bendix up front, 235/85R16 tires, 12-volt w/alternator, electric wipers and a modern radio in the glove box.