I briefly taught machine shop in high school. I was a vocational teacher for over 30 yrs but mostly automotives. I learned quite a bit but never had any gunsmithing type experience.
I wanted to learn so I watched several videos on the subject. Darrel Holland's, Gordy Gritter's tapes. Went to Practical Machinist website. I also asked questions of my gunsmith who was kind enough to let me watch. (he is my age and took the machine shop classes where I later taught) I took notes. I asked every gunsmith I knew their version of rebarreling. I read extensively on line.
Then I assembled tooling that would work for my old Sheldon. I installed a spider on left end of spindle. Got a few dial indicators with magnetic bases. Made a simple floating reamer holder. Practiced making threads. Made a few form dies from old rifle barrels. When I rethreaded and rechambered a rem takeoff as my first barrel and had a very hard time getting the headspace exactly right.
Found out about the Lambeth-Kiff Micrometer Adjustable Reamer Stop which made the headspacing a breeze.
Lambeth-Kiff Micrometer Adjustable Reamer Stop
I does cost money to tool up. Reamers are expensive too. BUT nothing can replace the pleasure of doing it all yourself and then seeing tight groups as the result of your labors.
I am certain your machinist friend could do it but it will cost some bucks to get the necessary tooling.