master is a manuel drum master. No pull when breaking. I do get a little less pressure from front's when bleeding. Brakes work, will lock the front wheels but seems to need excessive pedal force to stop. Nice firm pedal, no fading, not soft. Car was born with power brakes. Last owner changed to manuel because of poor vac with big cam. When i drove the car stopping power was horrible. Thats when i did the brake job. Much better but not right. I don't know the exact bore. The master is a replacement for a 68 GTX. The best way to discribe the feel is like when power brakes loose the vac and it takes excessive force to stop the car. Pedal is hard but not stopping very quick. Car has plenty of go now need the woe.