If I were to get a single shot for a 13 year old, I would consider the 243 Win (use 100 grain Nosler partitions), the 25-06 Rem, 260 Rem, 270 Win.
I would absolutely forget a 30-30, I dont care if you say 100 yds or not. Let's get real here, the 30-30 has horrible ballistics by today's standards. Get your boy a rifle that has a relatively flat ballistics capable of up to 250-300 yard shots. I started out with a 30-30 also, and I surely understand it's shortcomings, which are "many". I am as aware of it's history as anyone else, but that is not even near the top of my favorite deer caliber list. Limiting anyone to a 100 yd rifle is rediculous. As soon as you do, he will see the buck of his dreams at 225 yards. Make the right decision and get him a good deer caliber that is also "flat shooting".