You'll need to refer to the CPP instructions to be sure. The largest reservoir is usually for the discs. Front/back reference can be confusing, because the underfloor MC is mounted backwards from how it would be mounted on the firewall... Also, I think that all underfloor systems are dual booster since they are smaller diameter (7-8").
I really think that you are dealing with a booster issue (adjustment nut between booster & MC/low idle vacuum/defective booster) or that you need RPV's in your system. I have 4 wheel discs on my 3600 with the stock pedal with a CPP kit and everything works well. If it was a proportioning valve issue, I think that the rear brakes would at least lock up...which, if I understand correctly, isn't happening..
Last edited by Norcal Dave; 11/11/2017 3:56 PM.
