But the assistant boss conceded the Blues’ hunt may prove fruitless given that attribute is so difficult to come by.
A central defender who is naturally left-footed is high on Kenny Jackett’s shopping list this summer as he plots another League One promotion push.
Pompey haven’t had that type of player since Matt Clarke departed for Brighton more than a year ago.
Clarke was a natural on the left-hand side of central defence and was often able to start swift counter-attacks.
That’s something Jackett's side lacked last season as they suffered play-off defeat to Oxford and are keen to reinstall that quality to their ranks.
However, Gallen admitted the Blues will sign the best centre-half available – even if he is right-footed.
‘We would like that (a left-footed centre-back), but there aren't many of them so you end up trying to take the best player that you can,’ he said.
‘But it would be great if that player was left-footed.
‘It would help the balance of our team defensively and allow us to counter-attack quicker. Distribution would be better and it would help.
‘But there are so few options so you end up trying to take the best player.’
Sean Raggett is currently Pompey’s left-sided centre-back and featured in the role for the majority of last term.
Jackett’s considering whether to push the former Norwich man to the right-hand side, though, which would be a more natural fit for him.
But Gallen explained Raggett’s played on the left for the majority of his career so a decision is yet to be set in stone.
He added: ‘Playing Sean on the right is an option but it would only become an option if a left-sided player comes in.
‘If you speak to Sean, he's always played on the left-hand side and is more comfortable than he is on the right.
‘He wants to play on the left-hand side but then it would be an option and a decision for Kenny to make if we were able to get a left-footed player.
‘Kenny would have a decision to make whether to push Sean across, but Sean he is happy to play on the left.’