There is no relevant notice about the fuse box in the Haynes Owners Manual 1961-79. The German literature mentions the latest fuse box type under dashboard only. If you have the four fuses box beside the voltage regulator, so I can trace up from the electrical scheme:
1. flasher unit
2. stop lights
3. wiper switch
4. front and rear harness junction block (lights and rear screen)
There is no notice about the fuses value.