twisted,
The resh is not guttural. It’s a dental. Probably a trill or a flap, but even the American “R” is closer.
The soft Gimmel, linguistically, probably sounds like the Israeli Reish.
Kuf is probably closer to the “QU” (and if you notice, in Israel the transliteration for Kuf is Q).
There are many sources that point to the fact that Sin and Samech are the same letters, and indeed, are interchangeable.
Think “Va’eshoch in the Akeida or “Gal Sa’adutha”. Both in the chumash with Sins, but we spell with a samech.