I have a 66 with manual all around drum brakes and a single resevoir master cyclinder. I just blew my front right break line a few nights ago and before I repair it I wanted to ask a few questions. I plan on replacing the single resevoir with a dual resevoir.
1. If I repair the front break line now what can I do to prepare myself to do the dual resevoir master cylinder so I don't have to do the right front brake twice?
2. There are currently 3 lines coming into the preportioning valve (2 front and 1 rear) and 1 line connecting it to the master cylinder. When I convert this I assume the front two will get there own preportioning valve but what happens to the rear? Does this connect right to the master cylinder and is there another preportioning valve further down stream?

No proportining valve is required on a drum/drum system. All you would need is the dual master cylinder and the tee that is already there in the front brake line.