A bunch of lift companies make 4" lifts that still use the stock mounts. Seems that after 4" the geometry changes too much and requires the mounts moved to maintain a decent on-road ride. That and still using the stock mounts is going to start defeating the point of using longer arms.
TeraFlex, Currie, and RockKrawler come to mind as sources for pre-made 4-link JK control arm brackets (sure there are others). Off Road Evolution, Ballistic Fabrication and AtoZ Fabrication all make generic weld-on CA brackets. OR you could always make your own.
To cut off the stock mount near the gas tank is tricky, and from installs that I read not too much is salvageable of the original once removed. All those installs warn against using a torch or plasma cutter on that bracket for obvious gasoline-related reasons.