I bought a 1985 Trek 620 frame (longer chainstays and canti brakes) last year. In the process of building it this winter I installed a 130 MM wheel in the back and left it for a month out in my shop. Now that the polar vortex has released its hold on us for now I went back out to the shop with the intention of working on this project and found that the brake bridge has separated from the seat stay on the drive side of the bike.

I was building this up with the intention of riding it this year, I put about 1000 miles on a bike in a season, 50 to 150
miles per week with a couple of centuries planned.

The paint on the frame isn't the best and it also needs the canti mounts replaced on the front fork. Is the cost worth it or should I retire this frame and use another?

Suggestions?