Since I'm fresh back from a visit to a local frame builder (10 mins ago), with my repaired frame (new top tube), I thought I'd comment on this question ....
I second the recommendation for Ron Boi at RRB cycles in Chicago. His moniker on ebay is "13ron" :
He runs an ebay store named something like, "Trek 2a Bicycle Store" (now "Truck 2A Bicycle Store 4Tires"). He has been building frames since the mid 1970's and he recently sent me some pictures of an aero time-trial frame that he made from steel.
Another choice is Franklin Frames of Ohio, Dale recommends those guys a lot.
http://home.windstream.net/
The problem of repairing seatstays in such an old bike might be in finding the right type of seat stays. Most seat stays start out at a certain diameter, maybe 10-15 mm, then they bulge in the middle for the brake bridge, then they shrink back down:
http://www.novacycles.com/
11mm / 15mm - double taper (wider in middle) 14mm / 14mm - double taper (wider in middle) 14mm / 10.5mm - single taper 17mm / 12.5mm - single taper 16mm / 12.5mm - single taper
There are a zillion possibilities, but sadly, not very many of them are being made today, especially the "pencil" stays. You might want to measure your seat stay diameters and lengths before you contact someone about having the frame repaired. Better yet, find the parts online and take them with you to the frame builder.
- Don Gillies
San Diego, cA, USA