Front axle swap master cylinder/prop valve issue

[ReeseBobby]

I'm in the process of swapping out my front axle on my 1970 K20 to a disc brake axle. I purchased a master cylinder / proportioning valve from Summit and attempted to install them on my black brake booster. However, the booster does not correctly mate to the MC. The booster has a long rod in the center that does not attach to the new MC. The hole in the MC is too small.

Additionally, the prop valve fittings do not mate correctly with the original brake lines that fit the old prop valve. I was able to get the truck operational by leaving the old MC and Prop valve on the truck, but I know this is not optimal. Under hard braking, I can lock the rear drums up, and while the truck stops better in general, I don't feel the disc brakes much more than I felt the drums.

Will the drum/drum booster not work with disc/drum, or am I just using the wrong MC / Prop valve? I purchased the disc / drum setup from Summit and thought it would just be a slap on and screw in. Any help would be appreciated. Thanks!