When is a steering shaft toast?

[Metalaroundstone]

My 66 has always had excessive play in the steering staft. I decided to take the column out and see what's up. What I found was everything was in pretty good shape except the lower bearing had disintegrated and wore a very deep groove in the steering shaft. See pics below. In the second pic you can clearly see the grove and what is left of the inner bearing race. In the third pic you can see what is left of the outer bearing in the tube.

I have 4 (or more) questions:

1. How hard is it to find a replacement shaft for a 66?

2. I'm thinking that the shaft should be 3/4 in diameter from top to bottom. Is this correct?

3. I have been told that the shaft is not hardened so I'm thinking that if push comes to shove it can be welded and refinished to the correct diameter. Is this possible? Has anyone done this? Or is there another way of fixing this?

4. I have seen bearing for sale, but it also looks live the lower spring is heavily worn. Does anyone know where to get this spring?

Thanks