Awesome find! Ouch! How long does it take you to go through all of that?
It takes me about 20-25 min to go through a box of nickels.
I use a very sharp knife (Stanley) to cut about 10 rolls at a time;
then I grab one roll and peal off the wrapper and place the whole undisturbed roll on my right hand;
I use my left index finger to knock off the coins from my right hand on the table with my eye screening the coin;
when I see an older reverse or obverse I stop to examine further. I don't need to see the whole coin but just a third or 50% the coin would be enough to catch the older coins;
War nickel, buffalo, and foreign coins are unique so they can be easily separated;
After 10 rolls, I transfer coins on the table to a canvas bag and repeat another circle.
The knife has to be very sharp in order to cut through the paper wrapper quickly. In six years, I have cut my fingers twice

.
Initially it took me about 40 min to finish a box; Once getting used to the deeper strike of the reverse and obverse of early nickels I can do it much faster.
1938 has a unique strike of reverse and obverse;
1939-1964 have another type of deeper strike; The mintmark position on the reverse is another a giveaway.
1965 and after have the shallow type of strike.
My method is kind of intense so I normally don't do more than two boxes of nickels at a time.
I use ample lights (equivalent of 500w) to ease on my eyes.