All S76 models have blowaway power available
Apart from A, A+ and A++ (and by assumption, The standard C).
2 minute power in the 76 does not exceed the maximum design limit transmission torque. Utilizing 2 minute power will accumulate towards engine maintenance schedules. I believe 10 minutes of 2 minute power can be accrued before an engine tear down is required.
That's for OEI - if you have both engines sticking 127% Tq into the MGB I'm pretty sure that will require MGB maintenance action!