Not certain if this is exactly pertinent to Your thread/question, Chief $.02, but I feel that it's worth mentioning.
FWIW: You can change a Mark III trigger using newly cast, aftermarket parts, or simply check Gunbroker/Ebay, etc, for a parts kit, taken from a (court ordered) & destroyed revolver.
I bought such a parts kit a few years ago, because I wanted to change My early Mark III Trooper's trigger from narrow/grooved, to wide/smooth.
That kit was well worth the money expended, as I also received the entire gun, (minus frame), supplying Moi with extra parts, should anything ever wear out on one of My Mark III's.