Usually somebody in their tech staff will want a isolated ground conductor going straight to the equipment bonding bus in the service where the GEC and MBJ land. That might also serve a sub panel for the server room so all the circuits will share the same grounding path.
I think anything beyond standard 250 is usually snake oil. It is good to have a common grounding bus but where the ground comes from is not as important as getting all the equipment in the room bonded to that bus.
The ground bus plates an my radio equipment shelters were more like 4" x 16" and had a bunch of 1/4-20 tapped holes with brass screws in them already. They usually used a #4 cu solid to the ground electrode system, landing in the service disconnect can.
