With the geometry and sizes pretty much all set, it should be obvious by now that the rSogn would feature the same Pacenti MTB crown. This one has enough width for the Neo Moto 2.3, or 58c. The axle-to-crown length is set at 385mm.
The rear clearance would be set for the same tire, and will feature s-bend chainstays like those of the Drakkar. With this bend, one can set up the rSogn with contemporary road double cranks with outboard bearings, square-taper cranks with cartridge bottom brackets, and triple cranks.
Like the cSogn and dSogn, the rear spacing would be set at 132.5mm.
While we are at this, the rSogn with its capacity to take the Neo Moto 2.3 will have standard-diameter 9/6/9 tubing for all frame sizes. The head tube would be set for the now-ubiquitous 1 1/8" threadless steerer.