Are new handlebars available that are the same, or nearly so, as the early 70's drop, Randonneur handlebars that were available on the grand sports models?
Well, yes, to a certain extent. The attribute you are looking at there is known as "Flare" and is a current trend on nearly all "gravel" style bikes.
The flare on some of the newer bars can be quite extreme, to the point of being silly, but there are designs out there that keep a fairly classic look and give a few degrees of outward flair, such as the Cinelli Swamp, models from Shimano/PRO and any number of others.
Try this link for a look at some examples
You will see the main difference is that the V shape of the older bar you have shown is quite unusual: most of the modern bars have a flat top.
I hope this helps with your research.
Yes. Randonneur bars are still in production, although they're a little bit of a specialty item. Rando bars raise your hand position by putting a little kink near the center ferrule; modern bars raise your hand position by using a shallower drop, and work with modern brifters that give you a better hand position than old-school brake levers did.
Here is one example. The stem on this bike most likely requires bars with a 26.0-mm clamp diameter. The ones I am linking to are out of stock except for very wide options. Here's another option that comes with a 25.4-mm clamp diameter that can be shimmed.