Could it be a 1 in a triangle? I've seen that on Russian Sks. Anyway I still think it's a Tula letter series Sks.
I have a utg butt pad on one of my Sks as well , also strictly for length of pull reasons , feels good.
And yes Westrifle are solid in my experience.
I’ve looked again at the markings on my SKS from Westrifle. Actually the triangle on my SKS is very clearly stamped. However, that “thing” inside could be either a “1” or even a “9” not an arrow. That would indicate a refurb made in either Liski or Perm, Russia (Russian "Liski" refurb (formerly known as Ex-DDR) SKS Tutorial; http://www.sksboards.com/smf/index.php?topic=109529.0).
My extension is exactly a utg pad. Good stuff, makes a huge difference for me. I can clearly see the front sight now.