"two methods are common:"
Its actually 3 and you forget the most common: use a PLD.
Using a PLD has many advantages, especially if you use a larger one:
1) you can include the ALE latch
2) you can make inputs either polarity
3) you can latch events for the '51 to pick up later
4) you reduce chip count
4) it is a heck of a lot easier to reprogram a PLD than to change the layout of a circuit board.

Erik

PS PLEASE do not go to the antique store and use 82.. parts

Erik