Advice needed.....

The original had a 1" bore and you don't want that; that is a horrible set up for these cars. 15/16" is where its at. And rockauto has a nice new one for $56 if you can swing that. I highly recommend you put some 7/8" rear wheel cylinders on there too. Order those for a '72 Dodge D100 truck rear wheels. Those will bolt right on and reduce pressure to the rear for more balanced braking.