If you do the timing chains every 100,000 you should be fine, there are a few other issues butt most shops are scared to do the timing chains because they don't know how. The valve seats are only a common issue if it overheats, same with the head gaskets. The rockers tend to fall off when it sits an extended period of time, there are fixes for that witch only take a few hours to install on a good engine. I don't see a ton of sluged ones, they don't seem to have near the issues as a 2.7.