Let me add the supersonic test profile of the German J- 79 RF-4E, clean aircraft.
We climbed to 36.000 ft , selected reheat and accelerated through mach1 in a slight dive, regained FL 360 and accelerated level to check at least M2.2 as max speed , which some jets exceeded up to M 2.35. To reduce to subsonic speed the power had to be reduced to minimum reheat ( deselecting reheat could have blown the nozzle flaps), spedbrakes were extended and a zoom climb to 48.000 feet initiated.
AFAIK the German J-79 F-4F was doing the same profile, but was slower in top speed.