Basically what everyone said above.
you NEED leverage on these shocks for them to work properly on a higher speed application and for spring rate purposes. Those two literally go hand in hand with eachother because the leverage allows you to run high enough spring rates to actually push the axle down to keep the tires planted between holes. Without the leverage you’ll end up with something like a 100/200lb spring rate which has an effective combined rate of 66lbs. On both MarcyTechs silverado and Chris’s F150 I had them build the lower links about with the shocks. About 12-14” up from the Heim. Reason for this is to slow down the shaft speeds enough so the tires can actually drop quickly, run heavier springs in the 200/300 range, and gain travel. I want to say both trucks were strapped right around 23” total travel with a bit more left in the shocks. Both of the trucks ran standard 3.0x18” coilovers and bump stops and worked very well. Knowing what i know now i would change up the shock setups pretty drastically but they both got down and would put a hurting on a lot of other linked trucks, and worked a helluva lot better than leafs would.
Key notes to take away from this
-Shocks need leverage. 12-14” up the lower from the Heim is the business
-You need preload aka spring pressure at droop to make it work right, so make sure you have rear weight
-c notch or kick the frame. All the bump travel you can get is ideal. 12” up from ride height minimum
-do not mount the shocks to the axle, it sucks unless you drive smooth roads or short courses only
-this setup parties.