Category IV Building wind drift checks

[Robcat71]

I am trying to determine if utilizing the 70% or 0.7 x 0.6W = 0.42 applies when I am designing a category IV building with an ultimate design wind speed of 125 mph. That corresponds to an MRI of 3,000. So in order to determine the wind service loads from the 10 year MRI or 25 year MRI from the commentary, is there an additional conversion needed or can you take directly the ratio of the squares, ex. 75^2/125^2 = 0.36 to check at a 10 year MRI?

Thanks in advance!

 

[r13]

See the linked thread. Link