The normal VLE is 280/M0.67
The gear down ferry VMO/MMO is 235/M0.60 (activated by a switch in the avionics bay)
With this switch selected you will then get the FLT L/G DOWN memo displayed.
I cannot find any cruise performance figures for above FL290 for any weight.
As well as the FCOM limit disappearing the flight level caution note in the QRH (and FCOM) emergency descent procedure where it says you could lower the L/G has also gone.