Rear disk conversion issue

Sill low pedal and I haven't gotten back to rears dragging but, I'm convinced it is all related. While removing the SSBC gm universal MC, I realized I had the connections to front/front and rear/rear. It seems this gm mc comes with a lot of the generic pwr brake conversion kits. The SSBC instructions don't even say how to plumb the lines for mopar. It states front or rear as if it doesn't matter. No RPV in the gm mc. I bench bled the mc again and get a geyser in the front and fluid rolling in the rear. I don't get geyser to the rear with a quick pump. I'm wondering if the mc is bypassing and bad? Comments? I don't have a high press gauge to check but, I'm going to buy one for Kubota problem. I bought the 80s something aluminum 2 cap Raybestos MC39178. The Mopar mounting is smaller and of course has the deep hole. I have slotted the ears on the mc and I'll fabricate a spacer tomorrow. It's worth a try anyway. I know some of the Wilwood use gm 3.375 mountings and I couldn't find a generic gm aluminum one. Any suggestions? Craig