First.. the new Marbles tang sights "work", but I don't know of hardly any Savage 99 folks that want one on their rifle. For the same price you can probably pick up an older Lyman or Marbles tang sight - which, while not windage adjustable, is far better quality wise.
My top choice is probably the Lyman 29 1/2 or 30 1/2. Pricey, but one of the best.
Another choice would be a Lyman #1A, the early Marbles tang sight is similar but has a locking tab behind the stem rather than on the side:
More period correct would probably be the Redfield 70LH or Lyman 56S or 57S. A lot of the Lymans seem to have required some wood to be removed on the side of the 99 for it to fit properly, though..
For THAT vintage... I'd first go for a Lyman 29 1/2 or 30 1/2, second I'd go for a Redfield 70. Jmho.