Brake Questions - Help

New to the Forum, Hello All. I am working on a 1969 Barracuda that I recently purchased. I DO NOT have the build sheet and need some ideas on the direction I need to go on a brake repair. The vehicle is a 340 small block with front discs and rear drums. Here are the questions. Note : Please forgive me, I have done brake jobs but I am lacking information on the vehicle specifications here.

1) How would I know if the front disk brakes were factory installed or after-market? One of the pictures below shows the caliper and you can see "A71312" on the passenger side one.

2) Is the picture below a proportioning valve or a distribution block? I am concerned someone just threw on front disc brakes and did not install a proportioning valve nor install the correct master cylinder.

3) The master cylinder is manual and there is a "20872" stamped in the rubber seal gasket and made in "U.S.A." BUT both chambers are the same size/volume like it is for a 4 wheel drum car. Again, I am concerned someone bush-leagued the brakes and did not install a proportioning valve the correct MC.

4) The vehicle does not seem to lock up the rear wheels when braking and without a proportioning valve that would happen, right?

- Will

- 1iumtinrGBxy_umwcZnAh-nx5-JabczBM.jpg 1Tvt72SfUss09B3Gjt-Y3nLWnjtB-7cRn.jpg