[Short 3/4]

A late 60's early 70's dual master should bolt right in. You will have to bend your own lines though. Some places may say they have what you need, but I guarantee they will be wrong.
Those drums should be 12x2", 11" is 2wd and will not work. Cylinders should be available, but be sure they are for 4x4. Hardware is different for a 4x4 even though some parts vendors think otherwise. Re use what you have, or go someplace where you can match before you buy.
While your at it, this is a good time to go to self adjusting brakes like later 60's trucks had.
Once well sorted, those 12" brakes work surprisingly well.
Good luck
Tom