Drive line vibrations will be the big one. I see you went with a DC shaft. They don't always solve the problem, and tend to wear uni joints fast.
Other things that are typically needed with big lifts.
Adjustable rear links
adjustable panhard rods. Raised panhard brackets away bar extension...
Did you want that much lift?
Caster issues are the first worm out of the can IMO
Beyond about 3" of lift, you start getting all sorts of issues that require solutions and money. Maybe changing springs is a better fix rather that piling on band aids?