Dire Dilemma!! This is dread man, truly dread

[Kane]

You will see the shackles flex a bit as you described. Mine do this and I can bury the needle in my Jeep without a second thought. I drive a 1980 CJ5 with a 3.5 inch spring lift and 33 inch mud tires. I roll at 75 with one hand on the wheel and I track straight no problem. If it is all new then move on to the next area. Caster, toe-in and tight linkage are the main factors to worry about. You get those correct and it will drive amazing.

 

[johnnyreb]

31" tires aren't really that much over stock for that year. I presume by leaning you mean sag? Mine sags on the drivers side from years of being driven with only one person in it. I don't know what you mean by a small amount, but I would think there would be a small amount of flex. Did the shackles have much side play when you put them on over the bushings?
Have you checked your shocks yet? They'll make a difference in stability.