So what in your opinion would constitute truly original stock to the rifle?...
A truly original stock for this rifle, in my opinion would, first and foremost have NO arsenal star on the stock. It would have only the serial number on the but stock. And it would the same deep red finish but it would be laminate instead of hardwood.
...Having same font on both laminated and hardwood stocks in "И"-series is not enough? Even when this font is way different from fonts used by GRAU arsenals responsible for refurbishing?
Are you saying that there was only one facility that refurbished rifles. The lists I've seen indicate at least a dozen (likely more) separate refurbishment facilities throughout the USSR with both differences and similarities between the stock fonts used. There are numerous blatant refurbs with stock fonts that are identical those on original carbines.