I also run the split leaf springs on our 63 max wedge car. The split spring really works. I am not sure if they have it for the truck, but the softer the spring the better, as long as it holds the truck up. The air bag is a great deal, just haven’t tried it yet.
Project X went 1. 62 60' and never squealed a tire. I have a set of 4. 33 gears to install, this should help move the mass better. I have a new 2. 78 first gear in the works and this should also help. I believe that a 2WD street diesel truck with the available power and with the right tuning on the suspension , along with progressive nitrous will run a 1. 40 something 60 ‘