the main problem with that 4.7 is the timing chain set up, replace it immediately if you buy the truck, it should be done as preventative maintenance at 100,000-150,000 miles, the trouble you will run into with that plan is that most shops are terrified to work on one, they are not that hard. The chains start slapping and most shops say the engine is blown up instead of doing the chains, tensioners and guides. The other issues that come up are valve seats and head gaskets going bad when overheated (don't overheat it and those will not be issues) and the rockers falling off when parked a long time (there are thingies you can get to put on that keep them from going anywhere when the "lifter" deflates that are very easy to install before you have an issue). They are not a good engine to drive and ignore like a 318 but the issues are not insurmountable.