Thank you again for your inputs.
As far as I know, Nogawa produced the majority of his works in bronze. The company even advertised itself as the "manufacturer of Bronze Ware". I've also seen some of the Nunome Zogan works by him, as well as shakudo. But I don't think I ever seen a shibuichi work from Nogawa.
I also don't see any Tadakazu named artist listed on the SmokingSamurai website. May be just missing, though.