Here we have a virtually immediate correction in 𝓟. Oliver Cowdery initially wrote “now I would prophesy somewhat more”, but then he supralinearly inserted an ampersand without any change in the level of ink flow. Since either reading will work, the corrected reading is not the result of editing. The original manuscript (which is not extant here) undoubtedly read “and now I would prophesy somewhat more”.
Summary: Maintain in 2 Nephi 30:3 the use of and in “and now I would prophesy somewhat more”.