Having just done this, it is more difficult than you might expect as bikemig raised some great points that I personally had to deal with.

This was on another Japanese touring bike, a 27" Shogun 1500. No modern canti or v brake I tried would work. The pads would sit way too high, and the width of the posts were far too narrow, especially for a modern rim at a modest 17-18mm inner width. I imagine the Paul's suggested might work as they have a good amount of vertical adjustment, but the pads will probably still be spaced too much inward.

I ended up going with 80's era Dia Compe 987's that I found on ebay. There are quite a few other models of similar design that offer an added amount of vertical adjustment.

With new pads and compressionless housing stopping power is very good.