It Depends (NO, not those rubber things). The R&D 6 shot conversion cylinder for Remington has the chambers bored "Off Axis to allow case rim clearance. The ACP cylinders are bored "On Axis" to to the center axis of the barrel.
For Howell cylinders that fit Colt Pattern Guns, the chambers are bored "On Axis" however, there are only 5 Chambers. For the CAS game, there is an extra slot for the bolt that locks the cylinder between chambers.
For your application, your most cost effective option would be to use the 45 Colt cylinder for C45S cases and skip the ACP application altogether.