I think they are making a mistake going to the 14 inch barrel. The standard 20 inch is not exactly long to start with.
Just give it a folding stock and it will be fine. You simply lose too much velocity with that short barrel and the .5.56 needs all it can get.
I miss the M60, they were phasing it out for the SAW when I served...but that M60 had some serious fire power and range.