He doesn't need fast film.
The light is very strong in the mediterranean this time of year, especially in the mountains, and even if it's over-cast.
For mountain scenes you really need maximum tones and minimal grain to pick out all the subtle details in a vast scene with great distances.
ISO 100 will do just fine.
I have done the mistake of bringing mainly 400 film to a similar location. At least I have the memories, but not the pictures I wanted.