as for mods on LLY, Things I would do and in no special order, are:
EGR blocker plate
PCV reroute
LBZ Intake mouth piece swap (whole intake if you can find one cheap)
Pump rub fix
4" turbo back exhaust. I'd just take it to a Big rig shop. Most will install with proper band clamps for under $900
Tune
Drive it.
Also save up for headgaskets cuz they will go at some point.