Sounds like you are trying to ignore your 0.53 mach number calculation and have replaced it with 350mph.
0.53 mach at sea level is 407mph.
Do you agree that your original calculation was off?
What does that tell you about the quality of your theory?
I'm not trying to prove your theory based on what you deem an impossible speed. You are.
I'll leave you to do your own figures. So far they have appeared unreliable (a 1.2 mach calculation and now a 0.53 mach calculation).
And anyway, I am not certain there's a linear relationship between thrust and velocity.