Yes, for a deck of that vintage, Dolby B would have been the only choice for NR. I could try a Dolby C encoded tape on my CT-F1250 with Dolby B engaged to see what the results would be. Combining Dolby C with HX Pro has been my most preferred method of recording, lately.
Let's see if I have a few blues & rock tunes for you played back on my 1250:
Click on image to play video:
Nando.