Brake technology, no matter how sophisticated, cannot get around immutable laws of physics. Single pivot and dual pivot sidepulls can all endo a bike with the right brakepads installed. And you should want that. A brake that CANNOT endo is a brake that is not superior. Period. All brakes rely on the rider to apply the brake properly. If you are right hooked and your reaction time is too slow, you will either hit the car, or endo, but there is no brake made that can save you from both at once. Only being an aware rider who can read the situation and predict the unpredictable will save the day. I would consider it a real waste of money to build a 700C wheelset with new 70mm drums for an aging Schwinn 27" chassis. Dual pivot Tektro's with decent pads, or premium pads if you prefer, but if the DP's cannot stop you to your liking, then work on your stopping because it isn't the brakes that need improvement.