Sorry for the delay. Coach Pedro Carvalho offers this reply to your question:
No , you should not use the 10% difference. You will need to work more on zones 3 and 4. You have a good aerobic base , but at an anaerobic level your heart rate is going too high, because your system is not trained at that level, and heart rate goes higher in order to compensate for that lack of adaptation.
I hope this helps. Let us know.