McCarthy remains the national team's all-time leading goalscorer with 31 goals having played for the 1996 African champions between 1997 and 2012.
Tau has netted nine in 23 matches for South Africa thus far and McCarthy believes the 26-year-old forward can break his record if he is played in his favourite position by Bafana head coach Molefi Ntseki.
“I think Percy has got every quality to succeed in Europe and to surpass me as the all-time leading goalscorer in Bafana colours," McCarthy told South African Football Journalists Association (Safja).
"But I think when he does play for the country, they must play him in his favourite position.
“Percy has to play in his best position where he will be able to play the kind of games that you expect and that is to put the ball in the back of the net and chase that all-time goalscoring record."
McCarthy is followed by retired marksman Shaun Bartlett on Bafana's all-time leading goalscorers' list with 29 goals.
While Kaizer Chiefs striker Bernard Parker is the only active player in the top five on the list having hit the back of the net 23 times for South Africa.
"All great players have come and they have failed [to break my record]. It is not that it is such an impossible record to get, it is there for the taking," the former Cape Town City coach continued.
"Percy shouldn’t be played out of position. Every time I watch a Bafana match, I see Percy playing in a different position."
Tau, who has proved to be a top-quality versatile attacker, helped Club Brugge clinch this season's Belgian Pro League title while on loan from Premier League side Brighton and Hove Albion.
“If he is the most influential player we have, why should he be sacrificed? Lionel Messi [Barcelona] and Cristiano Ronaldo [Juventus] play where they love to play. Robert Lewandowski [Bayern Munich] doesn’t get played on the right-wing," he added.
"If you do that you are depriving the player to give of his best. If Percy says he is the number nine, he should play the number nine. Every other number nine should compete for that position.
"Let’s not shift a top player into a wide position to accommodate the one doing well at their clubs. The only way Percy will excel wearing that South African shirt is by playing him in his natural position."
Bafana will participate in the 2021 Africa Cup of Nations (Afcon) and 2022 Fifa World Cup qualifiers when international football returns.