A tiny update before I will undertake some of the major repair works tomorrow...
- Right petrol tank seems to be leaking too
- I have replaced the switch holder in the instrument panel with one that came with the bits and pieces. Some of the plastics that hold the switches on the original one were broken. I've kept the best switches from both of them.
- Most importantly: bled the brakes and renewed the brake fluid. I had to push the pedal to the metal before the car would (eventually) come to a standstill. Now it brakes with screaming tires if it has to.
- The rattle from the prop shaft is due to its rubber mounting halfway. I've ordered a new one.