Left-back Davidson is edging closer to full fitness after more than five weeks on the sidelines suffering from a torn hamstring.
And Parry, a summer signing from Cardiff, looks almost certain to be available following a similar hamstring injury, giving Irvine a welcome selection dilemma.
Ross Wallace, Eddie Nolan and Veliche Shumulikoski have all been away on international duty since North End's last outing at home to West Brom on October 3 but looked to have returned unscathed from injury.
Midfielder Barry Nicholson remains a long-term absentee with a broken leg but Irvine should have no other major concerns.
