If it were me, I would use a metal sleeve through the bushings if possible. This follows the same mentality as compared to your other post about the sleeve for the shock bushings. As the shackles is mounted to the frame inside a bracket, the sleeve does a couple jobs. It protects from too much torque and also makes the fitment of the bolt accurate, while providing a buffer between the bolt and the rubber, letting the shackle and sleeve spin around the bolt. Without it you may have to move up a size in bolt for a snug fit. Although you can get away without using one on the shackles in that the torque value is relatively low for shackles as they need to move and flex. But you will probably be replacing bushings more often as they would take more abuse without the buffer of a metal sleeve. But on the fixed mount locations on our FSJ you should be using the sleeves. But they should have already been pressed into the spring bushings from Rusty's. And with using metal sleeves in bushings, always use some form of anti-seize on the bolt going through them. Makes life so much easier for either you or others later if you have to pull things back apart. I used a lot of bad words, saw blades and death wheels in the removal of all my seized bolts and sleeves.
I think you could get away with using the OMIX ADA shackles unless you want to do some hard core wheeling in the Jeep. If it were me, I might pick up an extra at that price and carry it with me
, just in case.
To get the sleeve out of the old shackle you can use all methods if you are not going to reuse them. You can cut the shackles to pieces and remove the bushing and the sleeve then you can cut away the bushing with a hacksaw or even a reciprocating saw if you are careful. Or you can try the smelly method of using a torch to burn the rubber bushing out. In either case, you should be able to re-use the sleeve. Use some white lithium grease on the sleeve and pound it into the new shackle bushing. I like to use a rubber mallet so I don't ruin the sleeve with metal on metal contact.