Wangus - I'm not sure you have actually had an answer to your question
Also the IAS at the quoted speeds of 1400 MPH at circa FL600 (ceiling height) would presumably be approaching low speed stall speeds (IAS)?
- at FL600, the IAS at a TAS of 1400 MPH is a fair bit away from the stall IAS. I don't have the conversion tables to hand, but I'm sure someone will have.
It sounds like a fairly basic book there if it quotes a top speed in MPH.