Many folks "lift" their vintage Airstreams. I don't necessarily like the look, but I've done it.
My Overlander gained about 3" in ground clearance when I installed my new axles. The starting angle was the normal 22 degrees, but the fresh rubber meant I got 22 degrees out of the axles, plus I order the "high profile" 1" mounting brackets which gave me another inch. It actually went higher than I figured it would. Here is a photo of the results.
The new Dexter axle mounting brackets have little resemblance to the ones used in 1975. You are very likely drilling new bolts holes to mount up new axles. I have on the three trailers I have installed new axles.
We worked all winter on my friend's 76 Sovereign
. It needed it. We installed new axles under it also. My friend ordered the 32 degree starting angle as well as the high profile mounting brackets. Here is a photo of the trailer on the ground. It certainly helped ground clearance.