The bushing should push into the LCA until the shoulder on the bushing is flush against the bushing shell in the LCA. You can mostly see that here. If you're using the stock pins the shoulder on the pin won't sit flush like it is here, but the bushing should still sit flush to the LCA.
The "problem" with the poly bushings is that they depend on the old bushing shells. Definitely on the outer shell that sits in the LCA, and if you re-use the stock LCA pins they depend on the inner shell on the pin as well. If the old shells are damaged, misshapen, etc then the bushings won't work properly. That's not a problem with the bushing really, it's a problem with the old stock crap that's no longer to spec. As for the stock bushings, I'll take this space to say that the rubber inserts in the factory bushings are not bonded to anything. The shells are just pressed into the stock bushings with an interference fit. If you press the inner shell out of a stock bushing, you can pull the rubber out with a pair of pliers. The intent of those bushings was never to locate the LCA's, that's what the strut rods are for.
I have poly bushings on all of my cars currently. They are not perfect, and they are different from the factory bushings. Personally, I recommend using aftermarket greaseable LCA pins, which are made for the poly bushings. This eliminates the "squeak" issue that everyone complains about because you can just grease the bushings whenever they start squeaking. Poly squeaks if it gets dry, it's just what it does. It also eliminates the inner shell, the greaseable pins are made with the correct diameter for the length of the bushing so there's no need to re-use the inner bushing shell. The also have the shoulder on the pin in a place where it's actually useful, if you re-use the stock pins the little shoulder on the pin won't usually contact the poly bushing.
The other thing is that I use adjustable strut rods on my cars. Again, and this is my opinion, adjustable strut rods should probably be used even with the stock set up if you're concerned about handling or getting a precise alignment. The stock strut rods are just a "one size fits most" deal, and their design actually depends on all the play in the rubber bushings to get things close. When you start eliminating that play by using poly bushings in the LCA's or the strut rods, the length of the strut rod becomes a lot more critical. The poly bushings do allow the LCA to slide in and out some. They shouldn't allow a LOT of movement, if they do then your bushings are not fitting your old stock shells properly. But if you can adjust the length of the strut rods, that totally eliminates the issue of the LCA sliding. If the stock strut rods were the right length they would do the same thing, but, they're usually not once you start using poly bushings.
You say you don't believe me about the stock bushings not being bonded in there somehow? Well here you go. This is a QA1 tubular LCA. They come with stock rubber bushings and a new pin based on the old factory design (ie, uses an inner shell). I'm converting mine to Delrin bushings from Peter Bergman before I install the tubular LCA's. So here's the stock QA1 set up (yes, I gusseted a brand new set of LCA's, that's what the welds are).
I pressed out the pin, which usually takes the inner shell with it. To my surprise, the pin pressed out of the inner shell! Maybe this is because the bushing is brand new. I've actually had the LCA's fall off the old pins during disassemby because the bushings were so worn out.
I returned the LCA to the press, found the appropriate size rod, and pressed out the inner shell. Again, I kinda expected the rubber to come out with the inner shell, but it didn't. I then just pried the rubber out with a screwdriver. You can see the rubber takes a totally different shape when it's not compressed in the shell, and that the inner shell is squeaky clean- the rubber is just an interference fit. Which is why you're not supposed to torque the stock pins at anything other than ride height, the rubber bushing will spin and tear.
