drum to disc. anyone using an adjustable prop valve?

[500HP/SB]

i'm swapping a k20 disc brake d44 under the front of my drumed 1970 k10.

can some one please explain exactly what the factory proportioning valve does?

how does is split up the pressure?

if i dont use the factory gm part, and i leave it plumbed the way my drums are, the fronts will have way more pressure than the rear right?

can i just use a traditional adjustable valve like this
http://www.jegs.com/p/JEGS/755192/10002/-1/10165
to dial it in?

is anyone using something like this adj. valve/distribution block?
http://www.jegs.com/p/JEGS/762853/10002/-1/10165


i like the idea of being able to adjust my bias.
any input would be great. thanks