rabidfox, The early short chainstay and side pull braked 520 would be today considered a rando or sport touring bike. Dual pivot calipers can improve braking power and a 700C wheelset (also, 130 mm spaced hubs work well in a 126 mm spaced frame) can improve tire choices. Tektro has some long reach DP calipers that have been popular for 700C conversions.

Campagnolo certainly has parts suitable for a tourer, they're just in very short supply.

Brad