I have not done one on your model, but I have probably done a dozen or more slave replacements over the years, and a couple of masters.
The slaves tend to be very easy. Usually just 2 or 3 bolts, the hose, and the linkage bits. Flush/bleed the system, and you are done. Access is usually pretty good under the car. The toughest 'gotcha' would probably be if the hose fitting does not want to turn. Hate when that happens. Sometimes it's easier to just get a new hose, and cut the old one off. The old one may be rough anyways.
Masters vary. Not complicated, but access can be troublesome. I believe yours may be located behind the firewall, which can be a pain, and a bit messy in terms of fluid spill potential on the inside.
I would rate it a reasonable DIY project.
1986 300E 5-Speed 240k mi.