rear disc brake / prop valve question conversion

My car is disc/ drum and I converting the rear to disc. Can I use the existing prop valve or remove it and install an adjustable one? Thanks

You do not need a prop. valve with disc brakes in all four corners, all you need is a distribution block.

What you don't need is a disc/drum combination valve, which is what you have right now.

You may, or may not need a proportioning valve depending on how well you did your homework. If you choose the wrong sized rear caliper you may need a proportioning valve to dial out any rear wheel lockup.

what brand is that block ?

You left out too much information so the only answer that fits is "it depends".

picture is from Dr. Diff

thank you !