Using a 650b X 47mm tire you have the same outside tire diameter as a 700c road tire, so for your gravel bike you can run the 650b gravel tires for off road riding, and swap to 700c road wheels for road group rides and nothing changes with the geometry or gear ration on the bike.
Rims
Material: Toray T700 (Imported from Japan / Korea)
Size: 650B
External Width: 30mm
Internal Width: 24mm
Depth: 24mm / 35mm
Weave: UD / 3K / 12K / SLP Pattern
Finish: Matte / Gloss / Non-Paint
Spoke count: 24H / 28H / 32H
Nipple hole: External / Internal
Weight: From 1200g+/-30g
Rider weight limit: 120KG
Max tire pressure: 85PSI
Max spoke tension: 140KGF
Flatness: ≤0.2mm
Roundness: ≤0.3mm
Hubs
Powerway CT43
Novatec D411/D412
DT Swiss 350 / DT Swiss 240 / DT Swiss 180
Carbon-Ti X-HUB SP DISC
Chris King R45D
Spokes
Sapim CX-Ray
Pillar PSR AERO 1423
Highlights
30mm external wide / 24mm internal wide to fit wider tires.
2.6mm offset helps even out the spoke tension for a more balanced wheel.
Hookless design provides the best impact resistance.
With a nice aero profile and rim shape designed to help crosswind stability.