There's nothing unsafe about an axle above the springs. All the AD 1/2 tons came that way from the factory, as did countless other cars and trucks that had leaf spring rear ends. As far as putting heat on the housing, how the heck did the factory get those pads on there in the first place? Pinion angle is important as well as shock mounts and spring pads. The last TF I had I put a Firebird posi in (over the springs) and had the pads welded by a pro. I had that truck for many years and ran it empty and loaded with no problems whatsoever.
Flip away, be safe, be cool.
