[Ski-me]

No your front springs won't "flip". When you take the load off of them, you will get them to be flat. IF you want more lift, either find a factory 3 spring lift that's on heavy duty trucks/suburbans. A lot of 3/4 suburbans could have them. Or add a leaf in the pack.

With that said, the springs are probably worn out so getting new ones would be ideal. To level out the back, either add a leaf, install "zero rate" from ORD, or new springs.

You really aren't going to see much difference going from 4.10 to 3.73. I'd leave as-is. Far too expensive to "maybe" gain 1 mpg. Also, you will lose power so at highway speeds, you might even get worse mileage because these trucks push so much wind. 3.73's may make the engine work harder to maintain speed. Elevation also can come into play for power.

I don't suggest cutting/welding/piecing together any pitman arms in any way. Do it right and safe.