The Dutch sides of the 70s were pretty hard tackling, but football was a different game back then. Nowadays, the modern equivalent that is Barcelona, don't necessarily tackle hard, but reduce the possible actions that an opposing player can make by closing him down early, effectively cutting off possible outlets. I would tackling as default, pressing as high, and individually put pressing on highest possible setting for the 3 mids and 3 forwards. I've done that for my Barca tactic and it has worked wonders.