Great post Jocko_51_B3B !
I have a 1948 B-1-B with a spare engine which I have started to rebuild and has several exhaust valves frozen to the guides. The one that was frozen partly open I was able to use a large channel lock pliers to rotate back and forth to free up, BUT of course, those in the closed position don't permit grabbing with a pliers. So if you don't mind, I have a few questions relating to your post regarding welding nuts to the top of the valve head to provide a place to grab and twist free.
1. would you mind providing as many details as possible about your weldments: (all around the hex, inside the thread area, etc.)?
2. how large of a size nut did you use?
3. How critical was centering of the nut to minimize shear forces?
4. What welding system did you use (ie. Stick, MIG, Oxyfuel, etc.)?
5. How readily did the valve face bead accept penetration?
6. Did you end up replacing the offending valve guides along with those valves?
THANK YOU very much for any and all information you would share, I'm determined to save my engine block.