It would be helpful to see a pic of the brakes on the bike. These may have a longer reach than the dia compe 500g brakes which were once very common. They showed up on a ton of old Treks for example. You can make pretty much any old brake work reasonably well with a few tweaks. New cables and housing are a big help. So are quality brake pads. Kool stops are very good; dia compe grey matter are good as well.

I'd get the kool stop continentals:

https://www.biketiresdirect.com/prod...xoCxLIQAvD_BwE