When I first got my car (103 engine) I took it to the mechanic to replace this little hose that was coming apart. I already heard it was near impossible to just get it in there without major surgery..
I was away from the car for just a few minutes while I served myself a cup of coffee. When I got back I saw to my great horror & near heart attack, the guy using a hacksaw on the (head side) pipe. Now this was a reputable shop...
He calmed me down by claiming to have done this successfully many times. Plus the "damage" was already done. He had stuck a rag in the pipe beforehand, so no metal particles could enter the head (!).
Had I been there I would never have allowed him to take that route - However, it did the trick and did not take longer than 5 minutes to do so.
As opposed to a comment made here about replacing the water pump at the same time - I did not. My water pump still lasted another three years before it went south and had to be replaced.
Good luck and happy new year.