Power assisted disc brakes?

I just bought a 1970 chevy g10 cargo van. I dont have power steering or power brakes. I am ok with the steering situation but I want to add power assist disk brakes in the front and leave drum in the rear. I found a system that might have fit but it worked off of the power steering pump. Dont have one so this is not an option. Can anyone point me in the right direction where to start with this, or where to look. Oh the van is a 90" wheel base the short one with a 350 V8 and an auto trans. I think it is a turbo 350 but I am not sure yet. Also keep in mind that I am probably going to put a built 350 into this soon so the brakes need to work with the choppy idle and possible a manual trans.