I actually remember watching that race on Telly!! PMSL @ Murray Walker when he says 'and Barry Sheene is waving at Kenny Roberts' when he flashes the V at him.
I also saw an intereview with Barry where he said that Kenny & himself had decided that they would just entertain the crowd for the first part of the race & not actually 'race' each other till the last 5 laps or so!! cocky bu**ers