I've had a similar issue with MPB. I bought my disc brake conversion kit several years ago and when I finally got around to mocking it up, they had sent me items that appeared to come from several different kits, including the B-body interior linkage and proportioning valve lines that appeared to come from one of their Ford kits.
I looked up the proper parts on their website and then called them and the guy tried to insist that the parts they had sent were the correct ones, even though there is absolutely no way the linkage would ever fit under the dash. He even claimed that he was the Mopar guy there.
The one part that was missing was the little linkage (Heim joint?) that connects the pushrod to the top of the pedal. I'd use my old one, but it doesn't fit to their master cylinder. Plus, the proportioning valve block is a PITA to mount and plumb. Add that in with the giant dual-diaphragm booster and I'm thinking I'll just find a Mopar-spec power booster/MC combo and proportioning valve, probably from Pirate Jacks.