Brake Upgrades

I am in need of some advice here, a.s.a.p.
My son and I are building a 73 duster. the car was originaly
a slant-6 and we are swapping over to a small block V-8.
Of course we will need to upgrade the brakes to disc.
The problem is that I've read two sides of this story and am not sure
who is correct. One say's virtualy any body style will work so long as you take everything from between the control arms. The other one say's That you should only use parts from another A-body???
I've got a chance at a good deal on an 84 model 5th Ave but need to know for sure that it's gonna work or not.
Any help appreciated...
PS: I need to know as soon as possible, before the car gets sold to someone else.
:?: :?: :?: