I've made lots of trailers from those. Like he says Be sure and but the camber back in after you shorten them. Couple of things I would suggest. Don't use the mobile home tires, if you are going to use it much. They dry rot before they wear out, and they aren't the best to begin with. Get yourself some lowboy tires, I get mine from my farmers Coop for about 80.00, 12 ply, load range G or H! usually Cooper but whatever he has in stock. Run the required air pressure 90-100 psi. I have a friend that works in a mobile park that watchs for the older trailers. They have the multi springs. I swap him for the single leaf ones. You get a lot smoother ride if you can find the multi leaf springs. I'm sure you know about the little anti-spin lug, but that's important since you are using the brakes. I have been able to get parts for the brakes at NAPA if you find you need them.
Are you going goose neck or tag along?
Also if those axles been sitting around all that time be sure and repack those bearings!!! I found some of the newer trailers use really thin races and cheap bearings, had no trouble replacing them with good ones, just took them with me to the bearing supplier.
Keep the photos coming.
JD