You have already got a '73, a good choice for rifle. Since you went with 45lc, stay with it. Latch onto some Ruger Vaqueros in 45lc and that way all your cartridge ammo can be exactly the same and simplify things for you. Keeping things simple has helped me and I am 65 years old. If you don't have to worry about small stuff with your firearms it makes it better to concentrate on just what you will do with them, loaded up and ready for the firing line.
SXS shotguns are not as probe to troubles as a '97, but that is my opinion. Either one for a shotgun will work great for you. You can shoot an internal hammers SXS BTW.
Quicker is what is in the hands of quicker folks. I could hand my stuff off to a Badlands Bud and his times would not be all that much longer than with his own shootin' irons. In fact he has done just that a few years back, when I lent him a SXS and he normally shoots a slick '97.
Concentrate on getting it right and practice. I would love to see you a champion in senior or senior duelist.
As was suggested, get on out to a shoot. Most everyone will welcome you and let you try different brands. Just do it!