If the oil was really black I'd do a second change in a few hundred kilometres as the new oil will also start to break down the sludge and get dirty real quick - this puts the sludge back into circulation and increases the possibility of sticky lifters and the tapping noise again.. Do the filter as well.
"If anyone disagrees with anything I say, I am quite prepared not only to retract it, but also to deny under oath that I ever said it." --T. Lehrer
"The secret of success is sincerity. Once you can fake that you've got it made." -- Jean Giraudoux