These stones are listed by the Gwynedd Archaeological Trust:
Stone II is at grid reference SH66421363 “Standing Stone – Cairn”. I think this is an amalgamation of two records, one for the standing stone and one for Hafotty-Fach Ring Cairn. This may be a misinterpretation.
Stone I is at grid reference SH66601365, but they also list a third stone nearby at SH66591364. I can see some scope for confusion identifying one from the other in the field as they’re very close to each other. As I’ve failed to locate either, I can’t really help clarify the situation. Strangely neither of these sites appear to be listed by the RCAHMW.
Both these stones are marked on the Ordnance Survey Landranger map.