I have most recently had Head and Neck Cancer, a tonsil was malignant. I had radiation on my face, neck and chest area. I now have trouble swallowing, yes there is some pain, I wouldn't describe it as pins and needles. I had to learn how to swallow to get things down. It's kind of like the food goes past the back of my mouth and hits a platform, then I have to grunt, or make noises and help squeeze it on down. It's been 2.5 years since I was done with treatment and it is getting better. Foods that have a good "slide" factor are needed, soups, caseroles, etc.
Each person is different, the treatments are different even though it's still radiation, his will be different than mine, his cancer is different, so his results will vary. Don't put a dire picture on the situation until it's there, but expect to have some difficulty.
Good luck to your Dad!!