One of the positional alterations sees Muldoon move from flanker to number eight, accomodating the inclusion at openside of Irish international Johnny O'Connor who will be making his first start since rejoining the province.
Bradley will test out the strength in depth of his squad will debut appearances for former USA 'A' international winger Alipate Tuilevuka, who has joined Galwegians, and ex-London Welsh scrum half Rob Shaw.
Former Leinster prop John Lyne, who came off the bench against the Springboks, will also get his first start against Castres, adding to the new inclusions in the pack which include O'Connor, Joe Merrigan, Michael Swift, Andrew Browne and Michael McCarthy.
Two players who sat out the clash with the 'Boks - Danny Riordan and Darren Yapp have been passed fit to return at full-back and on the right wing respectively. The Connacht bench, which could include Academy players Liam Casserly and Sean Carey, will be confirmed closer to kick-off.
CONNACHT: Danny Riordan; Darren Yapp, John Hearty, Mel Deane, Alipate Tuilevuka; Peter Durcan, Rob Shaw; John Lyne, Joe Merrigan, Brett Wilkinson, Michael Swift, Andrew Browne, Michael McCarthy, Johnny O'Connor, John Muldoon (capt).
Replacements (from): Conor Muldoon, Brian McGovern, Andrew Farley, David Gannon, Ray Ofisa, Conor McPhillips, Tim Donnelly, Aidan Wynne, Ofisa Treviranus, Liam Casserly, Sean Carey.