Yes, it is possible to use standard GM rod in a Champion. However, you can not use standard plug with it. Due to the shortened slide length, GM rod will extend beyond front of the slide during cycling. For this reason you must use GM rod with existing reverse plug. Also, standard plug is designed to work along with the barrel bushing, part that is missing on a Champion due to utilization of the bull barrel. Theoretically, you can put GM rod, install new Commander size standard barrel, install Commander barrel bushing (cuts for it are already done by SA), install short plug with a hole at the front to clear plug during cycling, but why all of the troubles?
Regarding the shock buffers, yes you can try it. But do not expect your gun to be a reliable one. Generally, no one recommends putting the shock buffers in guns shorter than 5" GM 1911, since the slide movement will be restricted even further on already shortened gun. This will cause FTF & FTE's.
BTW, most folks install shock buffers in order to prevent exessive frame beating with +P ammo. This ammo is not recommended for Champion, and you will not see any abnormal wear with use of a standard pressure ammo along with a factory 24# spring.