Holster wise the Eastwood rig would be commonplace at a SASS comp but would not be allowed at NCOWS events as the Buscadero didn't show up until the early part of the 20th century, and this organisation have a cut-off date of (I think) 1899 for equipment. A visit to a BWSS comp will show you much leather which has its roots firmly in modern competition - slanted cross draw holsters, belts fastened at the rear, shotgun cartridge slides with angled loops etc. - rather than the American West. You need to go down this route if you want to be a competitor.
Firearms wise you obviously have a very limited choice of revolver but a great variation in lever guns and shotguns. The smokeless conversion revolvers have a great advantage over traditional BP pistols in that you can run through a full comp of seven or eight stages without cleaning and you chance of a misfire or jam is almost nil. Not sure how your Marlin would stand up against a slicked and short-stroked Uberti if you want to go for honours. The 1897 pump shotgun is very popular but takes a lot more practice than a side by side if you want to challenge the top guys. From a historical point of view, the "wild" West was over by the time this shotgun appeared.
Whatever you choose you'll have a great time and meet some great people - CAS is primarily a fun event, although there are one or two who want to win at all costs.
Redcat
