Great minds think alike. I asked about the same question back a couple of years ago when I had only one Handi. Tim steered me to "barrel fitting" in the FAQs. I had 3 barrels fit to the same frame at the factory, and since put them on their own frames. I put together the rest of the Handis you see at my signature line from components. The only one left factory fit was the original .45-70, my first one. I then swapped my ejector barrel with another member for an extractor, so now they're all home fit. It's easy, just follow the FAQs and give a holler here if ya get stumped.
The big advantage to doing it yourself is the lack of turnaround time, and sometimes there's a cost advantage.
Good luck, and let us know how you do.
Pete