The 1958 Savage 99 EG is at the beginning of the period when Savage drilled the bridge to accept Weaver type bases.
The 1927 99 G has no factory holes in the bridge, but in the early 1930's the Stith Company came out with an ingenious mount that utilized the top tang holes to mount the rear bracket and the rear dovetail on the barrel to accept a shroud for the front end of the scope. There is a special insert for the dovetail that attaches with a screw and two set screws to the front shroud. The scope must be pushed all the way into the shroud and flush with an inner beveled edge. Then the two screws attaching the rear mount to the scope can be tightened. The Standard Stith mounts accepted a 7/8" tube.
When I was able to find a Savage 99 Stith mount, it came with a 7/8" Lyman Alaskan 2.5x -- but the two rear screws were frozen and I was unable to line up the front of the mount with the hole in the dovetail insert.
Alas, my desire to become a Stith Lord was foiled by Jedi screws that would not yield.
Posters on a Forum devoted to Savage 99 collectors warned me not to mess up the two frozen screws because they are not standard and cannot be found.
So I sent the scope and rear mount off to gunsmith who has done excellent work for me in the past (Frank at Sycamore Hill Designs) with the request that he "do the right thing." With a one day turnaround ("Return of the Stith") the scope and mount came back with the original screws unfrozen and unbuggered.
The other Savage has a pre-Permacenter Lyman All American 4x scope ("A Tale of Two Lymans") with Lyman Tru-Loc mounts and rings. I like the pre-Permacenter because the Permacenter has garish white printing on the saddle.