I think the IPD in the goggles does not have nothing to do related cockpit dimensions perceived, but the PPI (pixel per inch), the pixel density of the HMDs panels, after to have the Quest 2 and then the G2 with different PPI´s, Quest more huge, G2 more close to the real size.
I think with the G2 I have the good scale more or less.
The 152-172 are very tiny inside.