Hi Ulf, I also have a '77. To get to the ignition lock, you may have to take the column out; it won't flex very far. I had to to repair my turn signal switch. The pinch bolt on the steering rack might be a pain and it may still take some additional penetrating oil and persuasion to get it to slide off the pinion shaft.
Sounds like your clutch problems are just hydraulics. It is a pain to bleed the clutch; the bleeder is under the car, and the hose arches higher than the slave or master cylinder, so bleeding it by the book won't get all the air out of the hose. Once you bleed the slave as best you can, stomp hard on the pedal several times and that will move the air out of the hose and preferably burp it out of the reservoir. I just bleed it once more, and it works fine.
I won't go into the silicone vs. conventional brake fluid wars; each has its ups and downs, but for sure they don't mix nicely, so unless you feel like cleaning all of the old fluid out first, stick with the conventional.