In your current lowest gear you need to do at least 6 mph. When going up a steep hill, the grade, your weight and that minimum speed will dictate how much power you need. The average grade is 6.3%, to go up at 6 mph with your weight that requires about 200W, however there are also parts with a grade of 12%, going up those at 6 mph requires 350W.

So what does this all mean? If you want to climb this without stopping, you need to be able to do about 200W for 20 minutes and you need to be able to do about 350W for 1 or 2 minutes and then recover and repeat a bit later.

You don't need a hill to train for this. Probably what would benefit you most is training the short bursts of power. You can do this e.g. by going all out for 1 minute and then recover for 3 minutes and repeating 5 times.