Here's some research into when exactly the cutoff points could be for DC 1985.
First here's a list of the comics published
the month that Crisis on Infinite Earths began:
Action Comics #566
All-Star Squadron #44
America vs. the Justice Society #4 -mini-series
Amethyst, Princess of Gemworld #4
Arak, Son of Thunder #43
Arion, Lord of Atlantis #30
Atari Force #16
Batman #382
Batman and the Outsiders #20
Best of DC #59 -reprint digest
Blue Devil #11
Camelot 3000 #12 -maxi-series
Conqueror of the Barren Earth #3 -mini-series
DC Comics Presents #80
Detective Comics #549
Flash #344
Fury of Firestorm #34
G.I. Combat #276
Green Lantern #187
Infinity, Inc. #13
Jemm, Son of Saturn #8 -maxi-series
Jonah Hex #90
Jonni Thunder #2 -mini-series
Justice League of America #237
Legion of Super-Heroes #9
New Teen Titans #7
Omega Men #25
Saga of the Swamp Thing #35
Sgt. Rock #399
Spanner's Galaxy #5 -mini-series
Star Trek #13 -licensed property
Sun Devils #10 -maxi-series
Superman #406
Superman Special #3 -special
Superman: The Secret Years #3 -mini-series
Talent Showcase #16 -out of continuity anthology
Tales of the Legion #322
Tales of the Teen Titans #52
V #3 -licensed property
Vigilante #16
Warlord #92
Who's Who #2 -maxi-series/reference
Wonder Woman #324
World's Finest Comics #314
And here are the last issues of comics before crossing over with COIE (using
this list):
All-Star Squadron #49
Amethyst, Princess of Gemworld #12
Blue Devil #16
DC Comics Presents #85
Fury of Firestorm #40
Green Lantern #193
Infinity, Inc. #17
Justice League of America #243
Legion of Super-Heroes #17
New Teen Titans #12
Omega Men #30
Saga of the Swamp Thing #45
Superman #413
Wonder Woman #326