Tactic rule should activate from 70th minute. No need to create another one. It sort of works like "if leading FROM 60.minute than make sub/alternative etc." Therefore tactic rule will activate!
I have in the past used that to waste time(not very ethical but still) - make a tactic rule leading by at least 1 from 70.minute sub will take place.
If I lead at least by one than still it is okay - fresh player comes into field.
But there are games where score is tied and I manage to score lets say near the end of the game. Than sub will take place during injury time and when opponent kicks off the ball game ends.