Unless it's a fresh motor or is already beefed up, I would probably stay away from it. I think you would be looking at alot of weight, lacking on power, and custom headers just to name a few. Now if you had an old pickup, that's a different story. The 400's made great torque and low RPM power, but you can't really spin them up real fast.
You would need a big block bell C-6 or an old cast iron 4-speed as far as trans.