Another bonus point win against Montauban, who were narrow 19-17 losers in Limerick in October, would see McGahan's men gain a home draw for the tournament's last-eight, while a win (without four tries) and other pool results going their way would still be enough for a home fixture.
The team selection sees Paul Warwick retain his place at full-back, with Keith Earls linking again with Lifeimi Mafi in midfield.
The pack is unchanged with versatile forward Donnacha Ryan, who was called up to the Ireland RBS 6 Nations squad this week, again having to settle for a place on the bench.
McGahan said: "A home quarter would be fantastic. That's an outcome at the end of the 80 minutes, but we have to navigate through that 80 minutes first.
"It's going to be extremely tough because Montauban are an extremely good side at home. Their results have been excellent so far this year.
"They had a good win against Sale there in the Heineken Cup. They'll be sticky and they certainly have our number after losing here. Maybe (they'll think) the result could have gone their way."
He added: "This is a Heineken Cup game and we need to make sure that we finish well. That has always been our intention to finish as high up as we can.
"Every opportunity out there to get a result, we need to take it and there's an opportunity to play well and we'll take that opportunity.
"The players have come back into training this week and they're very motivated to finish off this campaign very well, because as we know the internationals will depart for the Six Nations.
"We'll split up soon, so it's important that we maintain and finish on a real high. It's about maintaining focus this week."
Looking forward to leading Munster before the break for the RBS 6 Nations, Paul O'Connell is expecting Montauban to give his team a searching test in what will be the Top-14 club's final Heineken Cup game this season.
"Montauban have said a lot that they're ready for us. They didn't have the strongest team out against Clermont last week, but they've a very good record at home.
"They've won their last two home games against Bayonne and Biarritz and they've been playing very well at home.
"I've talked to Prendy (Mike Prendergast) about his time in Bourgoin. He says the French team that plays away from home and the team that plays at home are different.
"It's the last game of the European Cup for them. The European champions are in town and we've no doubt about the level of motivation they'll have for the game. So it's to make sure we're mentally right ourselves to perform this weekend."
MUNSTER (v Montauban): Paul Warwick; Doug Howlett, Keith Earls, Lifeimi Mafi, Ian Dowling; Ronan O'Gara, Tomas O'Leary; Marcus Horan, Jerry Flannery, John Hayes, Donncha O'Callaghan, Paul O'Connell (capt), Alan Quinlan, David Wallace, Denis Leamy.
Replacements: Denis Fogarty, Federico Pucciariello, Donnacha Ryan, Niall Ronan, Peter Stringer, Barry Murphy, Denis Hurley.