Ian,
Guinness may have given the record to this particular formation....but in the past I have been part of much larger formations.
Graduation Fly By's and Formation returns from Tac-X during Army Flight School exceeded this number during the heyday of Helicopter Training in Alabama and Georgia in the late 60's and early 70's.
The first few Days of the Cambodian Incursion during the insertion of lots of Troops by helicopter was one of them.
My Alcohol ravaged memory suggests I was in one formation of about 160+ aircraft....LOH's, Cobra's, Huey Gun Ships, Hueys, and Chinooks.....and darn near ran out of fuel when we returned to seven refueling points.
Going out was somewhat organized but per typical Army the return was pure Chaos.
Each Unit or Section of Aircraft had different LZ's and the Brief was pretty simple...."That bunch goes first...then you guys follow them....then you other guys follow that other bunch...then....etc.