g-body rear axle upgrade help needed!

[fonz3482]

Hello everyone, I'm looking into upgrading my stock 7.5 open highway geared rear axle in my 84 monte. I have 2 "free" options to pick from. I can get a posi 12 bolt out of a olds cutlass 442, or a ford 9" out of a 78 f150. Are either of these rear axles a good starting point? I'm trying to watch budget, so the cheaper the better. Fab. work will be free. Any advise or help to point me in the better and cheaper direction will be greatly appreciated. Just some background on the car that may also help some with advice. I plan to make it a good all around performer(street, strip, handle great). I'm gonna run a sbc with @ 400h.p. with either a turbo 350 or a t-10 trans.