The windows of Busaras are the facade, they provide the rhythm and express the original modular plan of the interior. Originally the blinds in the windows of the office accommodation had different colours so that a diagonal pattern across the facade was visible when the blinds were closed.
The original glass colour is visible on the northern facade onto Store Street. The darker glass facing the Custom House is not original.
No way should you be allowed to change them unless you wish to change the glass back to the original (which would be very cool imho).
The interior has been badly abused over the years, with the removal of the original kiosks, shop fronts, restaurant, furniture and signage. The basement is probably the most intact interior with perhaps the top floor restaurant a close second.
No I know very little about Busaras, I only researched it for 2 years
Currently converting 90,000 word thesis with illustrations, interviews and bibliography for inclusion on archeire.com