Highest absolute possible score is:
6 accessible disks on field = 60 points (autonomous)
9 disks loaded into an alliance's robots = 54 points (autonomous)
9 disks NOT loaded into other alliance's robots = 54 points (autonomous)
6 color disks in the pyramid = 30 points
45 own white disks scored high = 135
45+4 (=49) other alliance's disks scored high = 147
3 bots at 30 level = 90 points
Total is 570 points
But of course one alliance would have to have one absolutely awesome autonomous mode, and the other alliance would not score or remove from play even one disk, allowing the other alliance to have every single one. As unlikely as me winning Powerball (since I don't buy tickets

)
Realistically, the max is about half that, since the other alliance is likely to at least show up and take many of the white disks out of play.
Even more realistically, the real max should be around 200 or so. 2 30-point climbers, 33 scored high, 2 in the pyramid.