I would go with a larger chainring such as a 52 tooth because the small wheels are gearing it down.It should have a tall handlebar stem so you aren't slumped over the handlebars even before you crash from having no brakes. That's all it needs to be a rider to keep in the trunk of your car. Many times I've found myself with a few hours to burn and wish I had a bike to ride around on. Even with those cottered cranks, it would be handy to have.
So, bigger stem, brakes (one speed w coaster hub) and maybe a better seat and you are good to go. If this is for sale, I would ask the owner if they have the parts they stripped off it.
I found out what it was about 3 weeks ago when I saw one in real life and read the name on the frame decals.It's a Phillips Folda (as it says on the packet), and probably came out of a Raleigh factory in the late 70s or early 80s with a 3-speed Sturmey Archer hub. I don't know if it was a Raleigh design or they bought the frames somewhere in Europe, perhaps Italy or even Eastern Europe. It has the same type of cheap folder lever that I removed from my Romet Wigry and replaced with a beefier one from a Romet Jubilat, so I wouldn't bother trying to fold it as they can be tricky to get tight again. Phillips was swallowed up by Raleigh in the 1960s to become just another brand.
I have seen that chainwheel design before, I just cannot place it.