I just finished this job as well on my wife's 2014 RRS HSE (same 3.0L SC engine as the LR4) with 68k miles on the clock. The front lower crossover pipe was completely separated from its footing insert like the OP's and the valley of the block was filled with nice orange coolant. My experience:
TAKE LOTS OF PHOTOS to ensure things make it back to where they once lived, particularly the rear of the SC and the alignment of the black bracket and the two metal braces that make it up. More on that..
-Took some trial and error to find the fuel pump relay, remove, start and run vehicle until it stalls to depressurize the high pressure fuel lines which will need to be removed.
-Draining coolant is messy. Always.
-Thermostat and housing were a chore due to difficulty getting to and securing the clamps in an open position and getting the hoses off of the plastic housing. They've been on a while through many heat cycles. Get the specialized 24" flexible hose clamp tool, $20 Amazon.
-Supercharger removal was a bear but with patience, side to side rocking and CAREFUL prying along the sides with a small pry bar it did come loose from the two rusty perches. The AMAZON lift mentioned by others was sold out. Harbor Freight has one as well but it wasn't available to me locally. It would have really helped with removal and re installation as I did this solo.
-As stated, be careful of the little, fragile plastic knock sensors which sit VERY close to the SC perch.
-The back of the SC has a rectangular plate with the infamous black bracket secured at three of the 4 corners of the rectangular plate Getting your hands back in there to align AND fit AND turn the L-style torx wrench (25?) was the most time consuming and annoying portion of the job for me, particularly the lower left torx if I recall correctly. This needs to come off before the SC can be removed. Some people have removed the wiring, hoses etc that the bracket supports and then removed the bracket still attached to the rear of the SC but I found this to be more complicated than it was worth. I may have been wrong.
-The rear crossover pipe was pretty straightforward.
-Change SC oil, 5.1oz of the AC Delco SC fluid, two 4oz bottles required.
-Clean the SC and change the coupler in the snout. I got a rebuilt snout with new coupler and pulley off ebay, OEM only! Return your old one for a core refund.
-There will be a very small (1-2mm) gap where you connect the foot of the new upper pipe to the neck of the lower crossover pipe. That's normal. The upper pipe fits far enough into the lower pipe's neck for a secure fit.
-Copper anti-seize to the SC perch and hole for the next guy or the next time...
-Definitely get the hardware to make the gasket/SC guide pins as mentioned by the OP. Cheap from Home Depot, grind the heads off with Dremel or similar. It'll make aligning the gaskets and the SC so much easier when placing it back onto the block.
-The SC needs to be re installed as a unit en bloc. You can't really separate the SC into its componenets and reinstall piece by piece. There is a 10mm bolt on the underside of each side that you can't access once the center portion of the SC is in place.
-Button back up, insert fuel pump relay, fill and bleed coolant system.
A huge thanks to all on here, particularly jlglr4.
