Though the 777 Flagship Suite seats are huge, they're not really 92" in pitch. Recall that the seats are staggered. So when seats are reclined, the feet of one passenger are next to the head of the passenger in front (albeit separated by a rather high wall). I'd estimate that the true length of each row is more like 72".

An alternative approach: Per Seatguru, the three-row coffin config really does have 92" pitch. That means three rows jointly take 276" of fuselage space. The Flagship Suite config fits four rows in that same space. So each row must take 69" of fuselage length.

This reduces 777 F CASM somewhat, e.g. by approximately 25%. It also reduces the ratio of 777 F space to other seats on that plane and other planes. Not to knock the 777 FS config, of course, which I relish.