1985 300 CD

Trying to remove my right rear brake hose I have some across the most stubborn flare nut I have ever seen in my life. First I tried freezing it, then I tried vibrating it, then I put a heat gun to it, then I tried a torch. All the time applying copious amounts of penetrating oil. No luck.

I am going to have to cut the bugger out and replace the hard rear brake line.

First problem, there is a retaining clip that goes between the flare nut and the hose end. Normally you can just cut the hard brake line, but this time I have to get through that clip. Any suggestions? Looks like I need a cut off wheel, though access is a real problem.

Second, it is either buy a new brake line from Mercedes, which will be great if they are actually available, OR I have to make a new line. There are "kits" available on eBay which come prebuilt to various lengths with the flare nuts installed. Has anybody tried these before?