I did a little figuring and took the top 8 scores from each event in the decathlon, averaged them, and then put them up against either top 8 finishers each of the individual events' Olympic final. Some events have yet to take place so I used the finishes from the 2011 World Championships for those instead.
The Individual event scores will be posted first followed by the decathlon scores.
100m - 9.83 to 10.57
Long Jump - 26.57 to 25
Shot Put - 69.46 to 50.62
High Jump - 7.57 to 6.76
400m - 44.68 to 48.12
110m hurdles - 13.26 to 13.71
Discus - 219.52 to 166.34
Pole Vault - 19.06 to 17.29
Javelin - 269.91 to 221.16
1500m - 3:35.4 to 4.22.96
While not "world class" for their individual events these are still pretty tremendous scores in each event. Keep in mind the decathletes also complete 5 events, each day, over the course of two days while most individual performers compete in only one event per day and often only one event per meet.
It is to be considered also that an individual decathlete will vary in strengths from man to man, but I figured a top 8 average (the number of runners in a sprint final) would be the best option.
It would be interesting to see how the greatest sprinters would stack up in a decathlon. I doubt that the other specialists would far well at all, but a certain number of sprinters I think would do well with training (I don't think Bolt would be one of them as he just doesn't seem built for many of the events.