Sling studs wouldn't be original. Common to see them added though.
Leupold makes a one piece base for the 99, it works well. Weaver has 2 piece sets, though they had some bad ones go out in the last 5 years or so that are off. Most Weavers work fine, just a heads up. Weaver bases are the #14 and #19.
“
The Savage 99 Pocket Reference”.
All models and variations of 1895’s, 1899’s and 99’s covered.
Also dates, checkering, engraving.. Find at
www.savagelevers.com