IMO, your best bet is a new rubber torsion axle. Independent action gives a better ride than a leaf-spring set-up, and the axle tube serves as a frame cross member. Old rubber torsion axles become harsh as the rubber ages and gets brittle. I’ve heard many people remark after getting a new axle, “it’s like a whole new trailer.”
For the best ride, the axle should be matched to the actual gross weight
of the trailer- with some margin, of course- so if you’re planning an extensive renovation
, you might want to hold off a bit. Some renovations shave weight
, but many increase weight. Axles can be custom tuned at time of manufacture. A 3500# axle can be de-tuned down to as low as 2500#, for example.
The axle arm start angle can be specified (up to 45* down) to increase ground clearance and allow for larger wheels and tires
if desired. For more flexibility, the Flexi-ride torsion axle has splined, user-adjustable axle arms. Only caveat is the arms are shorter than fixed arm models, so the mounts will have to be relocated on the frame to keep the wheels centered in the wells.
frames have been known to break under the front corners. Inspect carefully and repair or reinforce as needed.
Best wishes on your project!