Hi Jonathan, Two ways to go : 1/ replace ALL of your steel lines and brake hoses. You'll be good for at least another 20 years. or 2/ install a dual master cylinder and split off the system by removing the distribution block and replacing it with one from a later year, split system. You don't unfortunately mention whether your 66 has disc brakes or not . If it does not, you might want to consider replacing the front drum setup with a disc setup out of a later ( 70 thru 73 ) Chrysler . All you have to do is find a suitable donor car in a junyard and take EVERYTHING from it - the master, the two lines that go down from master to proportioning valve, the lines from that to the front brakes, the spindle assemblies ; it is a bolt-on job. If your 300 does NOT have disc brakes, and you just want to split up the system, find a drum brake car, again in a junkyard, and get the master cylinder and the two brake lines and the distribution block . The difference between drum/drum cars and disc/drum cars is that the latter use a proportioning valve, and the former a distribution block. Either way, it's an easy swap on the '66 300 John