Former Heart of Midlothian captain Zaliukas and ex-Hadjuk Split and Mechelen defender Pandza have both been training with 'Gers in recent times and McCoist admits he could sign one or both of the centre-backs.
"I've made it clear we'd love to bring in a centre-half and Marius has done really, really well," he told the club's official website.
"He says he hasn't done an awful lot lately but you wouldn't know it to look at him because he is certainly in good shape.
"Marius has come in to train with us and is a very fit lad.
"Himself and Boris are two players we've been looking at and I'm very keen to strengthen that department.
"I'm not sure if there's a budget for both and I would need to speak to Craig [Mather, chief executive] about that.
"He's very aware of our concerns about getting another centre-back in."