I reckon that Christie could do a decent job at No.9 (certainly better than the other current choices), he's got the energy and work-rate to press and ball chase, he's comfortable taking possession and carrying the ball, positions himself well in and around the box and is a goal scorer. I have a suspicion that it hasn't been tried through fear of being accused of doing a 4-6-0. even though that was 9 years ago it still seems to hold strong in peoples minds.
Forrest can return to his favoured right-wing and CalMac can fill in on the left for this one, with McLean covering the centre.
Go with Devlin and McKenna purely out of the hope that club familiarity will have some benefit.