I think a different view point might help here.
This is what I think, with 16" open/10.5" closed shocks sitting at 14" leaves 3.5" inches of travel left call it 3" including bump stop. This will be nearer 3.5-4.0" movement at the subframe bolts as the shock is behind wheel centre so ratio is not 1:1. Now if you have 3.25"/85mm from the subframe bolt to the road which is less than suspension travel I think grounding is more an issue of ride height than spring rate. This leaves two options, 1: raise the ride height to >4" at the subframe bolt or 2: limit the suspension travel by fitting bump stop spacers this way you'll hit the bump stop before the floor after all thats why their there.
To check and set correctly you need to remove the springs and lower the car with just the shocks on.
Jez