73' B3 340 Duster pro touring build

Percentage....about 45% or 1 3/4" in the front, so It will ride right close to the middle of the QA1 range which is almost 4". As for the rear ??? I didn't get that far, and I sat Dave (Dad) in the trunk to compensate for fuel & back seat, he's almost 200 lbs....the rear dropped 5/8" at the wheel well.

If a 10" spring is only collapsing 1-3/4"....that is not even 20%

What am I missing?