just a thought but is there any way to find out if the seals in a hydraulic clutch master cylinder can handle brake fluid? Or if the seals from a brake master cylinder will fit into a clutch master cylinder?
Dennis Kirk sells Magura controls maybe check out there web site to see if they have what you need.
Also a little food for thought ,although I dont know anything about them. There is a motorcycle<?> franchise called Boss Hogs I think that they wedge a 350 chevy engine into a custom frame. Now I did have a quick look at one and it seemed that it had a power booster for the clutch. A cable operated lever that went to a diaghragm that operated linkage for the clutch. Whether or not space and practicality limits the idea of it operating a remote brake master cylinder is possible, might be something to give a quick look at.