That data sheet (F-4018) is for the final version of the film. Your 1997 film is two versions older.
The version of the data sheet that applies to your film is the September 1997 version of F-8.
The December 2002 version of F-8 is for the intervening version of Plus-X, but the D76 times seem to be the same as the earlier ones.
The official Kodak datasheets for Plus-X are no longer linked to from either Eastman Kodak's site, or Kodak Alaris' site (where there are links for current products).
There are, however, some remnants of links that still work.
The links to the 1997 and 2002 version of the Plus-X datasheet can be found through Tim Gray's excellent 125px website - see the Tech Docs link therein:
http://125px.com/techdocs/