If the car is pulling to the left you can bet something on the right is not working correctly. There is a chance that the new wheel cylinder is not working correctly but I would check the adjustment on the two front wheels first. There is a chance the brake shoes on the left are contacting the drum before the right shoe reaches the drum, thus pulling the car to the left.
Try this simple procedure. Jack up the front of the car so that the tires are off the ground. Have someone apply the brakes to about 60% of the maximum so you can still turn the front wheels, while the brakes are applied. Each front wheel should require about the same pressure from your hands to turn the wheel. If they don't, adjust the brakes on each wheel until both wheels require about the same strength to turn, thus assuring that the shoes are contacting the drums at the same time. I do the same thing for the back on my car so that all four drums have the shoes contacting at the same time. I have used this procedure for years and it works great.
About 2 years ago had the same problem with my 55 truck. By process of elimination replaced cylinders, shoes, hardware etc..still pulled to the right and often would lock up and skid.
It finally occurred to me that there was "another" brake adjustment.
Where the brke shoes sit at the top...there's an eliptical shaped bolt with a lock nut..By adjusting this you change the geometry of how the shoes relate to the drums. Worked like a charm for me. Dialed the problem right out. Not sure why all of a sudden this needed tweaking, but it did.
Possibly you have this adjustment on your ride? If not disregard all the above chatter :thumbup: