I've found the brake shoes from Kool Stop to be a good choice for improving older brakes - they come in a couple of different compounds (black, or salmon), have some adjustability for toe-in, are fairly inexpensive, and will work with a lot of different vintage brakes. One issue with them, however, is that they are made to be uni-directional, with a long "tail" that sometimes interferes with the forks on older bikes. In some cases, the tail of the pads gets caught up on the forks with the result that the brakes won't open up wide enough to get the wheel out. Kool Stop does make a version they call "Continental" pads which are shorter and simply rectangular - but they also don't have the toe-in adjustability, which in my view is a strike against them.
The good thing is that the longer pads can be easily modified - and here I'll show you how.
|Cuts like butter.|
|The cut is smooth and straight. When on the bike, the cut will disappear.|