I would build exactly what I built with the ninja 650 but I would change the following
Replace pds shock and swing arm with a linkage from a KTM 690. That gets rid of the tank mods. Probably. I would also run shorter travel. I have 300mm and I could get by with less.
Perhaps go custom on the tank, but that is beyond my skill level. My bike you can stand but the shape of the tank prevents it being comfortable for long distance.
I had also considered running the KTM 690 subframe and tank setup. This would get rid of huge ninja tank and replace with 3.2 gals. I would then augment with maybe a side tank opposite the exhaust. Now I could have a seat that goes all the way to the bars for better seating positions.
Probably would require a custom frame and a ton of work. I considered doing this as I have the parts to frame it up but I simply don't have the time or ambition to tackle another huge project right now. But it would be awesome
My bike is fuel injected, gets 40ish mpg. Has plenty of power, weighs 385 lbs and that is full of fuel. I don't know if I would want it I do a 600 mile day on it but I probably could. It will easily pull 75 all day long and rips past 100 when required.
To me the big thing is weight. It makes a huge difference. You know how fun it is to ride a 450 dirt bike. But adding 200lbs just kills the fun off-road. My ninja is pretty close to exactly what I would want but def needs another revision.
I will do it someday just can't dedicate the time.
We're not out here to rough it. We're here to smooth it. Things are rough enough in town.