Here is an absolute treasure … old film coverage of motocross in New Zealand back in the 1960s and 70s, courtesy McLaren Archives and compiled by Alan McLaren.
Here’s archive film from the 1973 NZ Motocross Champs, featuring Ivan Miller (NZ MX GP at Woodville winner in 1978), Hugh Anderson, Morley Shirriffs, Tim Gibbes (Woodville MX GP founder and winner there in 1962 and again in 1965), Ross McLaren, Alan Collison (Woodville GP winner in 1971) and Peter Ploen (Woodville GP winner in 1972, 1974 and 1975).