A lot depends on what you want to do with the car and other work it needs .
Is this a running car . Can you give us some pics.
If you want to stay lobuck then stay with what you have and try to go with a droped axel and some juice brakes,
If u go the MII route as I did be prepared to spend some dough.
Positioning of the new xmember is critical. I believe the original axel is not in the center from the factory. Mistake or on purpose I don't know but I moved mine 1 1/2 . If you are using full fenders all will be hidden but you will have clearence problems with the rack.
Then you still need to keep the original xmember for the radiator supports.
Then of course there is the steering linkage . 2-3 u joints and a support bearing.