It's the C330f you want to look for, this ticks all the boxes, you mention, there were seven interchangable screens made for it , the No2 split prism, No 7diagonal split prism are very suitable, and for photographing buildings there's the No6 checker screen she would find useful. I don't know if the silver lenses or the black ones are better , but I would imagine the coatings on the black ones would be improved. All my lenses are black and have given me no cause for complaint, she would find the 55mm wide angle ideal for buildings with the added bonus of being able to focus down to 1:1 for closeups, the 80mm standard lens is good for general photography, and the 180mm telephoto would be the most useful combination. I bought my Mamiya system second hand more than twenty years ago and have been amazed at the quality of the results for the cheap price, I was using Nikon cameras at the time, and comparing 10X8 prints the Mamiya blew it out of the water.