Maybe Lanse will comment on this.
I'd look for a good used loader and pay a weld shop to adapt the loader brackets to fit your tractor. You may be lucky if your buddy can spare the time to repair or rebuild the bucket on a used loader and only charge you for his direct costs.
Production of simple pipe loaders with hydraulic buckets ended around 1960. Take a good look at a modern loader, they are heavily engineered with a lot of custom formed metal pieces in tapered shapes. The pieces are aligned in special made assembly jigs and clamped together before they are welded. To make the same loader from flat stock and standard steel sections will require a lot of metal cutting, hours and hours of assembly layout and a lot of extra welding compared to the welds in a mass produced loader. It could be easy to make a loader way too heavy in some areas and still be too weak in other places. Manufacturers also buy their mechanical and hydraulic components in volume with OEM discounts and no sales taxes.
Sketch up the loader you want including mounting brackets and a bucket. Count up the pieces, then add up the total lengths of the cuts required and the lengths of the welds required. I'd guess you'll easily have 300 to 500 linear feet of cuts and welds. Ask your buddy how much time it would take him to fabricate all the pieces, prep the welded areas, assemble and align the pieces by hand, clamp them together, and then weld them. Ask what he would normally charge for that amount of work at his shop rate. The welding labor alone could be worth more than the cost of a used loader.
Honest payback to a friend like that would probably include reshingling several roofs, pouring a lot of concrete, and several landscaping projects. Bring your loader.
I hope I am wrong about the costs, it would be a fun project if you could weld it yourself.