I disagree as well...you over estimate. You got a good deal on that stock for what it is, and what the current availability is. Assemble your rifle, and enjoy the heck out of it whilst keeping an eye open for an untouched original. When you buy that one, and then sell this one...your "mistake" may be more like $20 instead of 450...heck you may even turn a profit. I know for a fact there are plenty of Krag sporters out there...I see them all the time on gunbroker. and there are plenty of people buying them too, and plenty more who would love to have your stock to make their hacked up sporter a military shooter again.
Of course, we would all prefer to have "perfect, correct, matching,..." - but for my two cents, if the US govt didn't really care about it...disassembling thousands of rifles at a time, tossing parts in bins, then reassembling into jumbled up but serviceable rifles...then that same treatment is the ceiling of my realistic exceptions (we always hope for more, but...meh...). If a govt arsenal had your stock, I doubt they would have cared about the edges on the finger grooves, a cartouche being sanded off, etc. If it was in the pile and fit and function were enough to make a rifle serviceable again, it was used. You should be as proud.