"The 727 was a solid, easy to maintain aircraft and in some areas superior to what's flying today".
Agreed. . . I fly a lot. Almost exclusively Southwest, which means 737. I got thinking about the narrow-body 7x7's and wondered why Boeing dropped the 727. I know it had noise issues and center engine could not be easily upgraded to a modern, more quiet, high bypass fan.
Why not upgrade the two outer engines and eliminate the third? You would then have all the benefits of the clean wing that the 727 enjoyed, and avoid the FOD, vacuum cleaner issues presented by the 737.