[1968chevyprerunner]

I have a 1968 C10 that I have just started disassembly on. The truck was my wife's grandfathers and is perfect for restore. All it is going to take is a few patch panels, painting and done. My question is this.....I want to lift the truck high enough to get 34" tires under it and give it a "Prerunner" look. Before disassembly I was running 31" tires with stock springs with no probs. Has anyone tried this before or have any advice. I was told that using 3/4 ton springs would give it approx. 2 " additional lift. I think I'm going to need around 4" to clear tires.