Here is the engine bay in my '65 Coronet. It isn't a close up shot but you can see the aluminum/plastic master cylinder that I used. It has the 4 to 2 adapter but as others have pointed out, if you use a cast iron MC then you don't need the adapter. I stopped using cast iron master cylinders years ago since they rust during storage, but if you drive the car on a regular basis and change the brake fluid every couple of years you'll be okay.