proportioning valve (to be or not be)?

Hang on I didn't see anybody post their tire sizes.

And a final FYI, on the street, rear discs are a luxury; the drums are perfectly adequate, even for staggered-size tires.
The only advantage rear discs offer is freedom or near freedom, from fade, and quick pad changes. But as a streeter,when and where, are you gonna need to take advantage of these features.

A/J have you ever drove a modern performance car with 4 wheel disk brakes?
The rear disks make a huge improvement in stopping power, my new Challenger R/T has completely spoiled me.
I also had the same mentality that drum brakes were fine on the rear until I bought that car.