Under 'modern airforces' I'd try and include anything post 1960s (yes, I'm old).
- ex-Yugoslavia & Romania - don't make Orao, but make a derivative of MiG-21 instead (split intakes, 'solid nose', better wing - some of thses features can be found on Chinese developments); French electronics if available. Replace also the MiG-21 & 23 with it; no MiG-23 for Romania. Version 2.0 with RD-33, HCMS, single-piece canopy, better eject seat, better electronics & missiles (cue MiG-21-93).
- India - do the same before jumping on Tejas
- CCCP - same in shape, but use more powerful engines to arrive at affordable and reliable fighter instead on the MiG-23. MiG-29 is 1-engined fighter here, powered by AL-31, more affordable and rangier.
- Europeans - make Rafale and Eurofighter 1-engined, not 2-engined = price drops down, earlier introduction, exports in many hundreds instead in dozens.
- UK - the Lightning with tailed delta wing, Spey on board = cheaper to make and operate, greater fuel capacity, much better range/radius = export success.