It's not worth looking on the FAI site. It's a bit of disgrace when you come to look at it for information on records, and the Search function is broken.
RMH's record was probably not for overflying Everest, but for altitude or altitude gain. So, it wasn't a record set for the first time, but a record broken.
David Broom broke a record with his sub 70 last year, which may have also been a first time record in the category.
There's more information here:
http://www.flymicro.com/records/