If I created the 797 I would have the plane only having one engine instead of 2. The engine would be different and not round. it would seat between 180 to 240 and have a range of 4,100nm for the regular version. (Medium Haul). There would be an option for an Extra long haul, 6,300nm
I would also have an option for 2 engines if the airlines didn't like the one engine idea
797-100
797-102 (Two Engines)
797-100EXLH (Extra Long Haul)
What would your specifications of a 797 be for your idea if you were creating the design?