McNulty has missed the last two games after suffering a dead leg in the first half of City's recent home win over Fleetwood Town.
Fellow forward James Hanson has an outside chance of being involved at the weekend as well, with McCall saying that the giant striker is currently rated as '50/50' for a place on the bench.
McCall said: "With Marc, he's took a severe bang to his leg in that Fleetwood game - he was bruised on his thigh and his knee - but at least it wasn't a pull or a strain.
"He has worked with the physio today (Thursday) and done everything needed so we expect him to join in training with us tomorrow (Friday).
"He should also be available for selection for Saturday.
"James is slightly different, with a little strain you have to be very careful.
"Having said that, he is one that could be 50/50 for a place on the bench. If that is the case, he'd be a great weapon to bring on if needed."
Despite impressing in last Saturday's league win at Chesterfield, City will make at least one change to their starting line up due to Josh Cullen's time away with the Republic of Ireland Under 21s.
McCall added: "Josh will certainly be a miss for us.
"He plays with Ireland on Friday night so I did joke with him that he could get a flight back for the Saturday game!
"We have three or four options that we could use to replace him and we will discuss it all as a group of staff.
"It is a good problem to have, and we have the ability to change things again during the game as well.
"We will look at what we can offer, what Shrewsbury are all about, and then we'll pick the side we think is best to try and get us the points."