Need help with Prop Valve

[PipsC10]

I have some questions about my brake set up, and how prop valves work. Hopefully someone can school me so I can finish buying my parts. Any help would be greatly appreciated.

My truck was converted to power disc/drum brakes before I purchased it so I have no idea what the set up came from. I do know that the lines from the prop valve to the frame are stock, which I have since replaced with stainless lines.

I would like to purchase a 9 inch dual diaphram booster with master cylinder combo, but all the ones I have seen with the prop valve are different than what was on my truck.

As you can see in the photo of my truck before I ripped it apart, the lines connected to the prop valve from the frame are both exiting from the bottom of the prop valve. All of the photos I have seen of new Prop Valves, one line exits from the bottom, and one from the rear/firewall side. So hear is my questions.......

1. As long as I am using a disc/drum prop valve, does it matter what vehicle it came from?

2. Does anyone know where to find a prop valve like the one in the photo, with both lines exiting at the bottom of the valve?

3. What about adjustable prop valves like the ones Willwood brakes make, can you just replace a stock valve with one of those?

I figured this was a good place to start, and I will probably call CPP or ECE to see if they know also. When it comes to brakes, Im as green as they come. Thanks everyone in advance for any help that can be given........Pip