[RichardJ]

I am using the same booster. It's from a late '70s or early '80s Chevy van. I wanted the booster against the firewall, because I don't like the MC hanging out almost to the front of the engine. I used the complete disc brake setup from a '76 3/4 T so I used that MC as well.

Your signature says "73-87 front suspension w/Disc". The '76 had a brake, Combination Valve mounted on the crossmember under the radiator. If you don't have the Combination valve, did they include a stand-alone proportioning valve on the rear brake line? I can see a distribution block/brake light switch in your pictures.

Your signature also says, " ??? Cam". Unless you have really weak manifold vacuum, I'd loose that huge vacuum reservoir canister.