Pictures of a Stith at www.savage99.com. It's a mount that requires no new holes, the rear goes on top of the tang holes, and the front uses the rear sight dovetail. Comes in 3/4" (most common), 7/8" and 1". Different scopes for different sizes.. folks here can help guide you.

“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