If you put a socket on the crankshaft pulley/damper bolt and turn the crank a little back and forth you can feel the timing chain play by hand and it kind of gives you a ballpark feel of how tight/sloppy it is.
I forget now,but I recall from the past that if it was more than "X" degrees play on the timing marks,a new chain was in order.
But like someone stated,the 5.0L roller chains last a long time.I checked the play in mine at just over 100,000 miles moving the crank by hand each way and it felt extremely tight,with just very slight play when turning right and left on the crank.