It's amazing that so many people are suggesting that these stops were added later, as clearly they are original. Just forget about that idea. The good thing is that the stops are low enough on the downtube that you can install downtube shifters above them, if you wish, or install bar-end shifters. If you've never used bar-ends, they take a little bit to get used to, but they were a popular option for close to 50 years because a lot of people really liked them.

I'll add, if this bike is offered for a low price and you're interested, and it fits, buy it. You'll almost certainly never even see another one in this nice condition.