Is that a U-bolt eliminator kit you got there? If it is I might have concerns with using a shim in the springs since the two plates where the bolt heads and nuts contact won't be parallel anymore. A degree shim won't allow the hardware to sit flat which could mininmize the hardwares functional strength.
You may have to cut reweld to keep this order of things in regards to your hardware. Just something to look for when you get into it. Good luck!
Oh, you asked about running 5.29's. Do it! remember with bigger tires the drive train spins slower and the gain is about back to stock (in relative drivetrain speeds). Also they're no noisier then what you're already used to when they're set up properly. As far as how fast you can drive....well...the tires will probably give you issues before the drivetrain will...
that ring gear is scrap iron now
and yes the odd bolt is probabbly your vibration
and what he said.
