Coil Spring Selection??

[Austin97C1500]

So we have worked out the final ride height we want on the truck. Parked the truck on a flat concrete floor and we pulled some measurements with the tape. The plan now is to ditch the leaf springs all together and build a 3 link with a watts link. We're going to run QA1 single adjustable shocks and their 2.5" coil springs. Looking at a couple charts available I'm thinking we need a 250 lb spring. In a 10" spring there is two offerings from QA1. One in their high travel spring and two progressive spring rates. If any one has any insights into what will work best on the rear of the truck for handling suggestions will be appreciated.

The truck is a 97 short wheel base C1500. 5" static drop up front, currently sitting on lowering leafs and shackles out back. 7-8" drop. Truck will be getting an LS3 Tr6060 swap.