I have a 2002 F-350 super cab long box with the 7.3 diesel, 140,000 miles. It has had it's share of problems, the rear u-joint goes out about every 40,000 miles, the rest of the problems revolve around having the big diesel, front wheel bearings, starters, alternaters, etc. But all in all I love the truck, it is the most comfortable and powerful truck I've owned in 30 years of driving trucks.
For me the 5.4 wouldn't be enough engine for this truck. If it's a grocery getter it would probably be OK, but if you are working it there won't be much power and the gas mileage will suck. My BIL runs a Plumbing and Heating business. He has a 2002 with the 5.4 that is just his backup truck now. Loaded down and pulling a trailer he would get 6-7 mpg. He was putting up with that but then it spit out two spark plugs within a few month and they weren't cheap fixes.
YMMV