So basically if you've fitted 3" shocks into a 2" lift you'll first up need to extend your bump stops before you turn those lovely new tubes inside out..
If your worried about brake line length then it's probably a good idea to upgrade to a longer line.. while your at it a braided kit..
But if they are shocks suited to a 2" lift then I can't see the issue..
Stock lines are fine but fit spacer if you like..
All you'll do it undo the top bolt, remove bolt, lift block and insert the spacer and insert new bolt..
No need to bleeding or draining etc..
2 min job..
13mm spanner or socket.