"Borusa was transformed into a living statue by Rassilon for his efforts; whether the statue survived the destruction of Gallifrey as revealed in "The End of the World" is unclear." 

 Come on ... In first series that is Rassilon's tomb, and Rassilon is discussed as a powerful, sometimes twisted, Time Lord from far back before recorded history.  In the new series he is a living being who leads the Time Lords to destruction.  Trying to tie the two together at all is farce.