Thanks for the pics. I should have asked you to get a pic with the MC lid off. Are the 2 reservoirs the same size? Looks like they are from the lid. Disc/drum masters will usually have a larger reservoir for the disc circuit. Also, that sure looks to me more like a distribution block from a drum/drum system, rather than a disc/drum prop valve (or more correctly, a combination valve). I'd want some others with more expertise on here to confirm, but it looks like a drum/drum setup to me. I'm no expert in brakes, just another guy working on his own truck.
It probably is worth bleeding the master to see if you can get more normal pedal. Also, any chance you have fluid seeping from a loose connection or split hose somewhere?
Thanks for the compliment on my build thread. You are right, my thread needs to be updated. Not many changes in the truck, right now I'm working on painting a few spots on the underside of the cab with POR-15, something I wish had been done when it was being painted! (what a pain to paint under a 'finished' truck (as if they are ever finished).
Jon