Drag car brakes

I’m in the process of putting rear disc brakes on my car. I had rear drum brakes with disc brakes up front.
I’m also redoing all the brake lines. My question is do I need a proportioning valve?

I have read some articles and some say PV is not needed if disc brakes are on all 4 corners. The PV is only needed if it’s a disc up front and rear drum.
Author: 79410aspenrt