The front headlamps will fit the pre-LCI but if they work no one knows because they'll need to be coded and you might have to buy other parts plus the LED headlamps are quite expensive, almost $3000+ for the pair. The taillights can be changed but again you need to find out what parts you need and you will need to have the, coded. And I don't see a point of changing the tails because they're exactly the same just darker. Hopefully someone on this forum will try these retrofits so we know the true cost and what exactly is needed.
The grille is the same as the night vision girlle you get the pre-LCI, again if you like the LCI grille you can install it on the pre-LCI bumpers. And why waste money on the LCI bumper, just get the m sport bumper which is exactly the same m sport bumper on the LCI. Swap the headlamps, put the m sport bumper and your car will look like the LCI model.