I have taken the time to read your whole story and maybe this will help. First of all a 7 inch power brake booster is rather small for your ride. A dual 8 inch recommended but you could even go with a nine inch dual if you wanted to. I would use nothing smaller than a 8inch dual. It looks like the master is mounted on the firewall and if so you dont need any residual valves anywhere on the system. The only time you need residuals is if you master is located under the floor and is below your calipers. Use the correct proportioning valve though. Disc front drum rear if that what you have. That is critical. Also make sure that you have no more than .008 to .012 clearance on the push rod at the master. Make sure that your master is for disc, drum and the bore size is 1 inch or better I have 4 way disc and mine requires a 1 1/8 bore master. I think that you shoould now have all the answers for any possible situation. A vacum pump isn't going to help anything unless you have all the basics done right first. I hope I didn't sound like a know it all in writing all this. But I have pulled my hair out many times till I finally got it right.