The 4.9L I6 made almost exactly the same horsepower as the 5.0L V8 -- I've always been kind of puzzled that the V8 was so popular. (The later 4.6L Modular V8 makes substantially more, though.) It's generally regarded as a pretty bulletproof engine. Straight-6 engines are inherently balanced, incidentally -- they don't need balance shafts or counterweights to run smoothly.
1990 E-250 Sportsmobile w/ penthouse top, converted when new by SMB Texas.