Earl should have come down here on his vacation time.
Ja 4-8-2 with 54" drivers regularly reached 85mph on the flats South of Christchurch on Passenger trains, two retired Enginedrivers living locally here will tell you they went faster. Our speedos were only marked to 70, there the needle stopped. Years ago I was in the cab of a Ka 4-8-4 being tested after wheelwork in my Depot, Jenks had it out in excess of 75.
In the early 90's NZR put speed limiters on the DX U-26C to keep it to 62mph, but we soon worked out that by putting the throttle back between the 8 and 7th notch and holding it there, the revs stayed up but the limiter was suppressed.
say no more.