Nikon V1 + tc20 III + 70-200

Can someone shed some light on this question.

Rule of thumb for using zoom lenses is to set camera speed to lens length. Example would be a 200mm lens would require 1/200s or better to prevent camera shake.

If you were to use the above combo, Nikon v1 (2.7x) with TC20 III (2x) and a 70-200mm VR II lens would your min speed be 1/200, 1/400 or 1/1080 to prevent camera shake?

Thx

Mike