I'm impressed you were able to get them off. I tried a few years ago and broke a screw off trying. Decided to leave them be. It looks like there is foreign material like a liquid metal in there. I would replace the gooseneck side anyways. That one can take a lot of stress especially in an accidental jibe.
Whenever I look at posts like this, I check the boat size and age first. Is the question "Can I make this functional and spend as little money as possible?" Yes, Large washers stacked around the boss sandwiched with epoxy would do the trick, provided the spring sits on top. But is this the best way? No. If your pockets are deep enough, replace the part. If you had somebody weld it, it may not work, Castings don't weld very well though a real good welder could get it done. But, it may cost the same as a new one.