The lebaron steering rack won't fit, but the hose connections and pumps are all mostly interchangeable. If the hoses are connected, don't sweat it, just make sure it doesn't leak.
The K-members aren't interchangeable as the K-cars are a couple of inches wider.
Get non-A/C belts and you're fine. You can cut down the A/C bracket to get easier access to the number 1 spark plug and drop a little weight, but its not critical since the non-A/C brackets are a little harder to find.
The Water pump is driven off the back of its belt on the 89 and later cars, so make sure you have the proper belt.
That connector on the firewall could be for the HVAC fan.
Corroded cap hold down screws are a common issue. Get a factory rain shield and anti-sieze for reassembly, then drill the screws out as they come in the caps. Gotta love aluminum distributors and steel screws. Worst case, you can get rebuilt distributors and they aren't hard to remove to get better access to the screws, etc.
The plug wire ends are the contacts inside the cap, so its more important to replace those than it is to replace the cap. You still need to replace the rotor, so you might as well get it off and replaced.
I would order a Shelby Charger Turbo radiator and hoses from RockAuto, since those will fit the engine and your car better than the LeBaron pieces. Cooling is critical in L-bodies due to their smaller engine bays, so its worth the budget hit to use new parts in that situation.
The Mitsu turbo is good for 18psi being overspun and generating more heat than power, an intercooler is pretty much required for anything over stock. The stock computer provides fuel for 14.7psi (the limit of the MAP sensor and programing), but the stock boost control algorythm will try to open the wastegate at 10-11psi and if it sees more than that it will cut fuel to the engine and flash the power loss light. So you need to trick the ECU to avoid this and manually control the wastegate via a controlled bleed valve. Read Gus Mahon's site for a better understanding of the solution.
Swapping turbos is an engine out or a head off proposition in that car, I wouldn't bother unless you need to or you find extra time and a good deal on a Garrett. Save it for next year. Keep an eye out for a Super 60 or similar turbo as that is where the power will come from.