Check out Coggan's power profiles. Again, assuming an FTP that's around 85% of MAP, this would give the athlete in question around 5.75W/kg, which is still in the 'worldclass pro' bracket. It's probably not unreasonable to lower all Coggan's figures by 5% for (95% of) pros in the era during which he gathered his data, which would put the king of the castle value at 6.08W/kg, and move 5.75W/kg squarely into the pro (upper) mid-table.
Except the subject of the test above was a Californian Sea Otter
Except the subject of the test above was a Californian Sea Otter