I did some digging and found the exact parts I have installed. The master cylinder/booster kit is indeed meant for a front disk, rear drum setup. Even though summit doesn’t mention anywhere that this is the case, it seems to be the general consensus in the product FAQs.
https://www.summitracing.com/parts/sum-760197
The proportioning valve I have is made for a disk/disk setup. I think when I bought these parts 6 years ago my idea was that I could use this proportioning valve to correct the fact that the master cylinder is meant for a disk/drum setup.
https://www.summitracing.com/parts/sum-760185
So maybe switching the two lines going in to the proportioning valve will fix it. Or getting rid of the disk/disk valve and getting an adjustable one.
An adjustable valve only affects the rear brakes, correct? How exactly does that work?