How about this as just a rough start:
St Valentines day class: 1911 pistol, 1927 Thompson, Pump shotgun.
Boogie class: Pencil barrel revolver, 1927 Thompson, Pump Shotgun.
Bonnie & Clyde Class: 1911 Pistol, Other period semi auto rifle or lever action, Pump Shotgun.
Untouchable class: Pencil Barrel revolver, Other period semi auto rifle or lever action, Pump Shotgun.
Snubble Side Match: Any snub nose revolver or .32 or .380 Semi auto shoots the pistol targets after the main match.
I think the big stumbling block is the Thompson. Not many people have them and even if you wanted to invest the $1000.00 or so they are in short supply. So alternate rifles are a must to get people initially involved. And then they may get a Thompson.