The limits at the top end were 530 knots CAS, M2.05 or T1=400 deg K (=127 deg C) At least, that was what they were when I worked on it in the late 60's. I seem to remember that the T1 limit stopped you getting M2.0 if the temperature was warmer than about ISA + 5 deg C, but you can work it out from the 1+0.2M^2 formula. From memory I think they had one of the prototypes up to M2.075, possibly faster.