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10/21/19: I removed the distributor from the truck, disassembled to troubleshoot the wandering timing and this is what I found.
* The grease cup had the spring and the fiber disk
* There was no noticeable lateral movement between the shaft and the housing
* I ran a dial indicator on the shaft and on the lobes using v-blocks. The shaft was perfect and the lobes ran out about .002”.
* I also measured the vertical movement on the assembly that contains the point cam and that read .035”.
* The shaft had quite a groove where the fiber washer rides. I measured it on V-blocks with a dial indicator and it ran true.

My thoughts:
* The .035” of vertical movement (on the cam assembly) will be lessened by the spring on the rotor and should not be an issue.
* The .002” runout on the cam lobes will make the timing vary.
* The groove on the distributor shaft is not good but since its even should not be an issue.

After cleaning and painting, I reassembled the distributor and installed it. I reset the points, re-timed it and readjusted the carburetor. This time I used a vacuum gauge to set the timing. I plugged the vacuum advance, set the idle to 450 RPM, adjusted the timing to the highest reading then backed off 1Hg. It ended up to be about 10 degrees advanced and still jumping back and forth, but it doesn’t seem to be quite as much. The engine is running better but I know that the distributor will need to be replaced in the future.

Maybe a HEI is in her future!