First find the total time James spends painting space marines: 20 minutes/marine * 6 marines = <<20*6=120>>120 minutes
Then find the total time James spends painting dreadnoughts: 70 minutes/dreadnought * 2 dreadnoughts = 140 minutes
Then add the two amounts of time to find the total time James spends painting: 120 minutes + 140 minutes = <<120+140=260>>260 minutes
#### 260