The pair are serving a one-match ban after picking up two yellow cards apiece at the competition.
Striker Gabuza has been in especially fine form in the tournament, netting three goals in four starts, while he also scored in Bafana Bafana's 3-0 victory over Mauritius in a CHAN qualifier this past weekend.
Veteran defender Lucky Lekgwathi, who has not played a single game in 2014/15, is also unavailable for the group stage tie due to injury.
The Buccaneers will depart on Thursday morning, and will fly for just over four hours before taking a three-hour bus ride to Dolisie.
The game will start at 16h30 (SA time) at the Denis Sassou Nguesso Stadium.
Pirates are due back in South Africa at 18h30 next Monday.