Airbus missed the bus back in the late 1990s when they decided not to continue with development of the A310 AEW&C project.
Airbus Industrie would have provided the air platform, design and engineering support, with ELTA providing an electronically scanned array radar and Raytheon the overall system integration. The radar antenna would have been similar in appearance to that fitted to the E-3.
Planned mission duration was to have been in excess of 11 hours, so it must have been planned to fit (5?) MRTT-style ACTs.
The A310 has the same fuselage cross-section as the A330 - so the A310 AEW&C would have provided rather more generous mission crew comfort than in a 737-based design.