Thanks for the info...
Your suggestion is possible but I can't determine if it is correct from the flight manual.
At max power and at a particular weight the stall speed for a particular flap setting is;
Flap 0 = 43 KIAS
Flap 15 = 40 KIAS
Flap 60 = 44 KIAS
The Airspeed calibration table for the particular flap settings only goes as low as 53 KIAS.
However from the table I can say that;
At a IAS of 60 kts the CAS for flap 15 degrees is 58 kts and for flap 60 degrees 56 kts