I don't think anyone sells new A-body hood springs. But they might still have them through Mopar parts. They made that spring design in A-bodies from 67-76. And maybe other cars used them. I've heard of guys with glass hoods using Omni? hood springs and they will fit right in.

Are you sure the spring itself is broke? When I got my 68 Barracuda in 1993 the spring stud that is welded to the cowl broke it's welds. That holds the end of the spring. The spring assy will flop from front to rear. The hinge is fine, just doesn't have a spring to it. Been that way ever since! When you open the hood is leans to one side. Still stays up.