Good morning, Mike;
Yes, when the original SR-2 came out back in September of 1958 (predating the Nikon F by seven months), one of the lenses listed as being developed for the new Minolta SLR cameras was a 180mm focal length lens. There may have been a prototype shown and photographed, but it never did make it to North America, nor was it offered for sale in Japan as far as I have been able to determine. It was also mentioned in some Minolta camera literature as being developed for the Minolta SR camera line. Nikon also did things like that. They would show a prototype at Photokina, but some of them never made it into production for some reason.
That focal length of 180mm was fairly common in that era, oddly enough. This may have been more related to rangefinder cameras more than anything else. A 90mm focal length was very popular for rangefinder cameras. They did go up to longer lengths also, such as the 135mm and the less common 150mm length. The 180mm length was actually getting into the area where a reflex housing would be a better way to go, and usually at 200mm and longer they were provided for use with a reflex housing. Still, it did seem that having "double the length of the 90mm" was a logical way to go, and you could work with a 180mm lens, but the rangefinder would not be all that effective with that focal length.
My odd Minolta ROKKOR lens? It is an early 35mm preset lens with an f/3.5 aperture, as I recall. I need to talk with Dennis Lohmann and with Henrik Robek and Andrea Apra also. I do not know if Massimo Scotti's English will allow us to have any conversations. My Italian is limited to just a few words.
Enjoy; Ralph, Latte Land, Washington