i would like to give you more informations about these guns...i m a collectioner of black powder guns replicas and i can answer to all yours technical questions

first of all i m sure that you knows that the blondie gun is a colt navy 1851 in a 36 inch caliber...(octogonal barrel)
the tuco s gun is a sudist copy of the colt navy 1851 because in this case the barrel is circular.the real name of this model is "griswold an gunnison" in a 36 caliber either. historicaly the gun s frame is not in steel but in an alliage of "bronze" (sorry i don't know the name of the metal alliage in english")
the production bought some italian copy of the great gun firm uberti wich was the historically speaking the first firm to produce very good quality replicas of black powder guns...(first productionstarted in 1958!!)
the guns used in the gbu are not like the original guns because as you wrote before the conversion gun appeared later after the civil war
but it was more practical to use and safer for actors... (ask benito stefanelli he was a specialist as master of weapons...)
the angel eyes gun is a remington new model army in 44 inch caliber...
the color picture of the gun in josey wales is a model of conversion "colt 1861 army" it use normal metallic cartridge
the other one are colt 1861 army . only used with black powder (cap and ball system)
the difference between the 2 models is the steel stick under the barrel for the black powder model (in french it is named "levier de chargement " or loading *levier*
and as a conclusion the 2 enormous gun of clint in the movie "josey..." are colt walker in cal.44 the most powerful (and heavy!)percussion colt of the black powder colt history:
Nice to hear an honest opinion .....and not for once a all in your face "I think know it all " view from Cigar Joe