I did a swap like this on an '85 not too long ago.
You need the front guards, lower valance panel, headlight support panels, lights, grille, light surrounds, and the rubber trim from above the bumper. You can change to the earlier aluminium bumper, or you can keep the plastic bumper, but it needs to be moved up about 20mm, which requires modifying the brackets.
If you have AC in working condition and don't want to open the system, that presents another challenge. This was the case with the conversion I did, so I cut sections of the headlight support panels out to allow the hoses to pass through them without being disconnected, it took a bit of work but the end result was really neat.
The way the AC condensor mounts is a bit different, but the solution was fairly simple, I was able to bend the brackets on the condensor, and bolt it to the headlight support panels with bolts and spacers tubes, again the end result was quite solid and neat.
With an '86, the shape of the plenum panel below the windscreen is different, so the shape of the panels doesn't match up. You would need to cut up an early and a late bonnet to make one that matched properly. I think the early bonnet fits the later plenum shape without hitting anything, it just looks a bit odd.
An "in progress" pic here:
http://zyrex.org/gallery/Cars/acw/Misc/IMG_9703.JPG.html