I would not add a PU/PE scope to a non ex-sniper. I would enjoy the M91/30 for what it is, an artifact of history, the main battle rifle of the Soviet Union. If you are interested in a sniper clone, there are inexpensive ones out there. Although, I wonder if this is a type of Bubba-ism. Of course, I tend to over think things.
Visit SAMCO. They have real 91/30 snipers sans scope for $229. You can get a repro scope, mount etc for about $200. This is what I did for my PU shooter. Of course you can visist R Guns and buy a real PU for $800.