The 1950's 99R's came standard with sling eyes, not studs.
I've heard reports that some of the newer Weaver bases are off. I haven't run into one, but I haven't bought a new set in the last 3 or 4 years. The Leupolds work great, just cost more. Or you can keep your eyes open for an older vintage one, Redfield one piece bases are pretty common for standard d&t'd 99's.
Congrats on getting a 99! And good luck at keeping it at only one. They tend to be a "can't have just one" type of gun.