Do you mean biased cold for a Musicman, or compared to some other number? Is there objectionable cross-over distortion?
Musicman amps are typically biased quite cold as they are running very high plate voltages. It seems odd that they have removed the bias adjust pot in this later version of their amps. Perhaps they had a reason .
What voltage are you reading across R51 and R54?
If you look at some of their other models with the bias trim pot, I'm sure you could add one the same way.