You didn't indicate in your post - have you pulled the front brakes apart to clean, lube and check condition of the shoes? If not, I would highly recommend you do so. The freed-up cable may be working ok now but you should know the internal condition of your brakes.
I suspect most folks acquiring these old bikes don't really tear into the brake system, assuming everything is ok if the bike stops when brakes are applied. One of the first things I do with any older vehicle I acquire is to investigate the brake system. Your life depends on it!