Very nice Geo!
I would agree with Paul too. From experience so far, on such projects in future (including my own Ventura), I will be airbrushing any joins or small details in White first, then going over the whole surface with Tamiya (White) Primer.
Their White primer is better than their Matt White (TS27) IMO, with no problems glossing, decaling, and matting.
Haven't had much success so far airbrushing large areas in White, that seems better for interiors and smaller details (wheel hubs, spinners etc)