I just put a new set of Tektro R559 dual pivot, long reach brakes on my Raleigh Sports, along with a pair of vintage mountain bike levers. Now the bike actually stops. The stock steel brakes and the weird self-adjusting brake levers made for brakes that were hard to squeeze, tentative to stop and whose reach changed at random depending on how hard I had to squeeze the lever to stop last time.
I have not built the new wheels nor mounted the stainless fenders, but the 650B conversion is slowly coming together. I am waiting to assemble my next spoke order to build the wheels, and when they are done, I will mount the new fenders.