Congrats on making an excellent "buy"... it appears you got a REAL bargain! Your rifle, in the condition you described, would normally bring about $500-$600.
According to Doug Murray's book (the REVISED 3rd. Edition), "The Ninety Nine", on page 3-59 under "SIGHTS", the factory began drilling & tapping the "EG's" in 1957, so your 1954 model ("F" in the Boss Code Code oval) was not "D & T'd" at the factory. However, if the job was well-done, that doesn't take away any of the rifle's value as a "hunter".
Incidentally, they made "EGs" from 1935 until 1960... serial #'s 350,000 to approximately 1,060,000, according to Murray.
My own Model 99, an "EG" made in 1953 (#709XXX), has a 3x-9x by 40mm scope on it and it averages .7 to .75 inches (3-shot groups) at 100 yards off a bench-rest using my handloads (.300 Savage).
When I first shot my rifle and got these kinds of groups, I thought my rifle was unusually accurate. Since then, however, I've noted that a good many 99 owners indicate their rifles shoot as well as mine, so the Model 99 is apparently a consistently accurate rifle.
Again, CONGRATS on getting such a fine rifle at such a low price... you did quite well. :grin:
Strength & Honor...
Ron T.