Nothing as for problems!
As long as you retain the same wiring from your car or utilize wiring from the same year bracket as your car you'll be fine(98-01 and 02-04). If you can find an IP harness with ATC and a ATC head, definitely a good time to do the swap if you have MTC.
Wiring from any of the LH models, Intrepid, 300M, Concorde and LHS will swap between the different dashes encase you or anyone else is wondering. All plug and play.
If you're painting your dash, clean it well, because if anyone ever armour all'd it or used some oil based product on it, the paint is going to separate like oil and water. I've found spraying a reducer or cheap paint on it first and wiping it all down tends to bring out all the chemicals. This is a trick me and a friend use when doing body work and painting.
Oil and other products are tremendous buggers.