If the car tracks down the road straight down the road without the brakes applied then your problem is in the brakes. All parts being good in both front drake setups, the problem is the left brake is applying sooner than the right. This can be cured with the brake adjustment. Start by adjusting the right side with lees play than the left. You may even need to loosen the left side adjuster. Being 60 years old, when I started turning wrenches, 4 wheel drum brakes were the norm. We were constantly fighting this problem.
