People that are good at brazing and welding can do pretty much anything you want to a steel bike. However those people have skills that are worth a lot to other employers so it's difficult in many areas to find someone that will want to fix your bike for the little you probably are willing to pay.
If you do happen to have a bike builder in your area that builds steel bikes, they might take it on as a charity case. <grin>
But as above, you do need to consider it might just be time to try something more modern. Though the older bikes are the prettiest bikes to me, I found out the new bikes have been the most fun to ride.