McGeechan - a midfielder for Scotland and the Lions in the 1970s - is selecting his all-star XV in a series of articles in London's Daily Telegraph.
He named Kirwan on the right wing and Lomu on the left, with 1970s Wales and Lions great JPR Williams as fullback in the first instalment, published on Monday (Tuesday NZ time).
McGeechan said Lomu was "unique'' and his impact on the sport was "immense''.
"He was built like a train, and could run like one. But he could also really play rugby. Lomu’s skills were honed on the sevens circuit with New Zealand.