My girlfriends 02 GTP started ticking shortly after I bought it.... but then the inside of the engine looked like it was full of dirt because of coolant and oil being mixed for so long. After the LIM gaskets were swapped I flushed it with oil and whatever "flush crap, lol" I could do. The ticking was a lifter not pumping up and now 15000 miles later the engine is still quiet. My engine is starting to look more reasonable inside now, and I pulled the fill spout off last oil change to see what I could. I am nearing a clean looking head casting underneath whereas it looked like mud before.
You could swap lifters especially if you have higher mileage while you are in there. Her car only had 70K on it at the time so I didn't bother.