Best bet for converting to hydraulic is to talk to Martin Hadland about it.

Ive converted other cars, but not a cossie, so dont know the ins and outs of it in the same detail as he does, but effectively you change the pedal for one with a master cylinder (possibly using one pikied from another car or a brake one if you are doing it on the cheap like ive done in the past) then you either fit a generic slave cylinder onto the standard mechanism or you swap it for the bits martin supplies to do the job more neatly.