Originally Posted by putback
Yes you can get all the parts you need to rebuild the original spring axle from various sources. You can even get the brake shoes relined and shackle components from a spring shop. BUT heaven help you if you have a problem on the road. With a modern X, either torsion or spring, all replacement parts are readly available. Not so with the rebuilt vintage, you could be sitting side the road a few days waiting for parts. Also remember "spindle fatigue" on an old X. The cost of damage resulting from a broken spindle would most likely buy 3 new torsion axles. The final cost between a complete new X and completey rebuilding an old one is probably less than $200. All things considered that ain't much.
Be aware, that new style brakes will not fit the old style drums, which are too deep to accept the new brakes.
The outer edge of the drums will rub against the backing plates, unless you have them machined down.