I've done some homework, and found that the water pump is turning in the right direction.
If I were to have a new radiator built, there is definitely enough room to make it plenty thicker, thereby increasing the coolant capacity.
59 talks about adding an external bypass to the water pump, and I'll have to do some more homework to better understand that possibility. What he said is how it's acting.
Also, all of the sites that talk about coolant capacity say the 350 needs 17 quarts, which would include the block and heater core to fill. The 348 and 409 call for 23 quarts. I'm thinking of draining the coolant that is in the truck now and measuring to make sure just how much coolant it does have. I know when I flushed and refilled it this last time, it took one gallon of antifreeze and just over another gallon of distilled water to bring it up about an inch above the core. I also installed a new pressure cap 13#.
Having a new radiator built can be done here locally, but it would cost me $800 or more.
Again, I appreciate all the help. You can be certain I'll be doing the happy dance in my skivvies in front of the post office, and take an hour to draw a crowd when this gets straightened out.
