Thanks again guys!
Yes, as Martin reported we tried all the methods suggested above to get the clutch to engage. None worked, unfortunately. Reluctantly, and with much hope in avoiding, we pulled the transmission. As others have reported that is a chore! After removing and inspecting the cover and spring assembly, clutch plate and disc no rust or obvious reason for malfunction is apparent. The throw out bearing appears to be good, with free movement as expected. That part was apparently used in all 3 speed transmissions from 1938-1950, according to the Master Parts Catalog (1929-1950). It measures 1 7/8” long. It did appear, before transmission disassembly began, to move as needed. The Disc does have a stamp indicating it was rebuilt, which tracks with the transmission having been rebuilt by a vendor used by the previous owner. I am wondering if that might be the wrong part? As may be recalled the truck has not been operated since the tranny and engine were rebuilt sometime around 1990.
We have not inspected the clutch fork ball, but given 52Carls observation, that will be done.
As I indicated in my first post about this I know virtually nothing about this stuff...but that is changing fast! I will also add there is no way I could have gotten this far with the help offered here and a couple of buddies locally.
I am open to any suggestions on how to proceed.