Thorne has missed the last two matches after being forced out of the action with a neck problem during the recent defeat at Exeter and is desperate to return as McCall's struggling side bid to kickstart their faltering play-off challenge.
McCall said: "I'd rather have him fully fit for six games than half-fit for seven. Thorney wants to be out there with us, but we've got to make sure that he is 100% right.
"We're hoping it's settled down now, but if it means he has to have another day's rest from heading, twisting and turning and just keeps working on his fitness, then we will do that."
Midfielder Paul McLaren is also in a fitness race and hopes to shake off a niggling calf problem that has restricted him to one appearance this month.