HI I have built many old bikes into Motor Bicycles, and from the look of that frame it's NOT done-for. Just check really close for cracks, when the metal is all clean, a "springer" of any sort, or even a hydrolic front end will reduce the pounding that the frame would take from riding.
All this said you are NOT going to be a curb-jumping, off-road maniac are you? If so please pass by everything that is vintage and special, and buy nothing but cheap, new replaceable stuff so the good stuff will be saved for normal riding.
I can show you some cool ones I built if you like,
Mike