The hair you want removed is very specific, and in a small area. You are best suited for Electrolysis treatments. You will get a natural looking hair line in just an hour or three of treatments, based on what you have said. After the first clearance, you will only have to see your electrologist on a regular schedule so that she can remove the other hairs as they come in.
You will have to let the hairs grow for a day or two so that your practitioner may be able to grasp the hairs, but at the end of that day, if your practitioner is fast enough, you will have the entire area cleared out.
Please do your best to find the best practitoner in your area. Get recommendations from people who have had electrolysis and are finished, and happy with their results if you can. If not, let us know what area of the world you are in, the more specific the better, and perhaps someone here can lead you to someone who is good enough to trust this job to.
When done properly, your hairline will look as if it naturally grew with a higher hair line from the day you were born, and it won't look artificially lined.