If I get a Newton leveling kit or a 2.5" spacer, would it be possible to add a 1 inch spacer to it to make it a 3.5" lift or would that put too much strain on certain suspension parts and make the brake line too short?
I think its too much to stack spacers on a spring like that. But you can put a one inch spacer on a leveling spring. I have a 2.5 inch ICON leveling spring and a 1 inch TEI spacer on the bottom of it for 3.5 total inches of lift. You will also need an adjustable track bar to get your axel centered.
No, the brake lines are fine. Im also running a 5inch block in the back. Heres a pic with Pro Comp 35x12.50s. I am going to go with a 325/60/R20 next time i get tires, they are a little bit bigger than what i have now but not by much.