These guys...
https://www.howellarms.com/ruger-old-army
These guys do have them in 45ACP, and in stock $335 blue, $365 stainless.
https://www.kirstkonverter.com/ruger-old-army.html
Who knows what's going on with Taylor's, ???
https://taylorsfirearms.com/hand-guns/cartridge-conversions.html?cat=88