I flew the simulator profile of an F3 vs FOXBAT at 65-70Kft at M2.5+ lots and lots of times and also instructed it as well. As the jet or its Skyflash are no longer in service then I'll happily explain my experiences. The F3 would go to 50Kft at M1.3+ without too much difficulty at all, it would even go higher (I know!
) but we didn't have the AEA to support us above 50Kft if we had to 'step outside' or if the pressurisation failed (above 50Kft you will suffer the 'bends' and even higher, due to the lower pressure, your blood will probably boil!
). Anyway, you would accelerate at the tropopause to M1.2 when the intake ramps would kick in and then you could continue to accelerate and climb keeping the FOXBAT as close to 'beak to beak' as possible - depending on the type of Skyflash the snap up was around 20-30kft and you would look to get a rocket off as close to the top of the Launch Success Zone (LSZ) as possible and then at least 1-2 more before getting anywhere near the LSZ for an ACRID (backing it up with a Sidewinder or ASRAAM as you got really close!). As your combined speed of closure was around 40 miles a minute then it was all over pretty quick! A stern conversion was not an option against a M2.5+ FOXBAT as my personal best was just shy of M2.2 in the F3 - also at max combat you were pushing fuel through the engines so fast that even with full internal tanks you had ~10 minutes until they ran dry!!!
I hope that helps?
LJ