Magnum Exhaust on a 70's A Body?

I saw a posting on putting 90's magnum manifolds on a early a body. Wondering if anyone tried on a 70's a body? I actually have one on the passenger side. Anyone have any luck on the drivers side? I know with ps it will not work,but with manual steering and some clearing work on the steering housing,will it work? Are these manifolds any better flowing than HP ones?:-D