If I was doing a complete axle replacement I would investigate independent suspension with torsion suspension, not leaf springs. May as well put disc brakes on it as well, you will love them. I would also look into Vault hubs, Dexter makes them. I have them on my tandem axle boat trailer. No maintenance for 5 years+, sealed system.
Sourdough (Danny) went with disc brakes and an independent suspension from Performance Trailer Braking. I used them for my conversion to disc brakes. They may have a service tech near you, or may not. At least talk to them about your options.
https://performancetrailerbraking.com/