You have to take 3 things into account
1) PPE or personal protective gear.. or just protective gear, like body armour and your helmet. At speeds over 70kph and especially on a road with traffic I would consider motorbike gear, open or full face helmet, long pants and long jacket, both reinforced, reinforced gloves, or even light body armour.
2) Your bike skill, level headedness, maturity, reflexes, comes with bike experience, motorbike exp would help a Lot also, and age.
3) Your bike itself, preferably with good front suspension at least.
I would be happy keeping up with traffic on 60kph roads, the traffic does 60-70kph. I wouldnt be comfortable on the highway at 100-110kph speeds. 70-90kph speeds.. not sure, possibly if i was wearing good gear.