ND filter problems w/ HVX 200

[Luigi Tadiotto]

A question: if you use a light meter,i.e. i use a sekonic 398 deluxe III, how have i to set up it when i use ND filters? There a slide called HIGH, but i cant tell how much is filtering the light…
If you say that there are 3 stops with 1/8 and the hvx200 is 320 iso, can i switch to 1280 iso for a proper translated reading?