Proportioning valve

So gathering my parts for the disc brake swap on my 72 Dart and I have a question about the prop valve. I grabbed one with the knuckles, calipers, etc, that is setup for power brakes. I am not going to power brakes but I am swapping the master to a manual disc master cylinder.

All the online articles that I have seen state to get an adjustable prop valve.

I have done the disc swap on a Duster and we used the prop valve from the donor car and it worked just fine.

So need some opinions here. Adjustable or donor Prop valve?