This shot was during a long test flight, pushing close to M3 at about 62k feet. I noticed it required a high nose attitude to maintain level flight at that altitude, despite the high airspeed.
What you say re the model sounds sensible to me. It's already very good, and the realistic cockpit really makes it work, much better than reusing the Su27 from FC3. If I were permitted any requests / suggestions, it might be for some more skins with more details on the fuselage and tail, like the picture in this article. https://hushkit.net/2020/12/18/i-was-the-first-foreign-pilot-to-fly-the-mach-2-8-mig-31-interceptor-heres-my-story-by-air-marshal-anil-chopra-retd/
Anyway, many thanks for doing this, and for your patient help re the gauges!