A '72 Sovereign
will have Henschen Dura-Torque axles, and presuming that they've not been replaced in the past ten years, they're shot and probably have been for twenty years. That causes a lot more issues than just frame drag and can lead to body/frame separation, interior separation issues, and rivets popping. You should be able to see tread in the wheel-well looking at the trailer straight-on from the side. If you can only see an inch of sidewall above the wheel, your axles are in fact shot.
You have a number of choices for new axles and several ways to mount them; all of which will require the services of a competent welder. Were I going to do it, I'd replace the current mounts with weld-ons that you can bolt the axles too such as Dexter offers. You have a choice of "down" angles that will all raise your trailer, as well as varying the height of the weld-on mount.
Do your homework here and elsewhere online on the various axle brands, and then work with the manufacturer or a local supplier to get the right axle and axle mount for your specific situation.