Post Reply - IBM Carbine ?stock "upgrade"?

Although there are not markings on several parts that I see, it looks like an inland flat top bolt. I know the safety and rear sight "upgrade" was a common rearsenal for the early carbines, but I was curious what you all think about how they affect value. When I look this weapon up in Fjestad's Blue Book 40th/newest edition, page 2148, he puts the carbines in 4 groups (Reworks and commercial mfg, Original Type I (flip rear sight no bayonet lug), Original Type II (adj. rear sight and no bayonet lug), and Original Type III (adj. rear sight with bayonet lug). To me that says this is an Original Type II rifle. For IBM rifles, the difference between original Type I and Type II in value is about $500 in near perfect 98%+ condition and drops to about $100-200 difference in the 90-95% condition range. Less than 90% condition the difference is about $100 or less. That would certainly make refitting those original parts less appealing for investment purposes considering those parts would cost more than the $100-200 increase in value?   The stock however strikes me as a bit out of place, hence my original post requesting advice on whether or not to "upgrade".

Thank you for your patience with me as I try to better understand this amazing piece of U.S. military history!