The Centers for Disease Control and Prevention publishes growth charts for kids. A 6-foot 1.5 inch 297 pounder has a body mass index (BMI) of 38.6. Each of those three numbers would be very far above the 97th percentiles for a boy just turning 14 years old (97th percentiles for a 14 year old boy: 27.8 kg/m^2 for BMI ; 5' 10.5" , and 170 lbs ). For a boy just turning 13, the 97th percentiles are 27 kg/m^2 for BMI ; 5' 7.5" , and 158 lbs.
http://www.cdc.gov/growthcharts/charts.htm#Set3
In the YMCA tackle football league in which I played as a 12 year old in the KC area, I don't think we had a general weight limit, but we did limit the ball carriers to persons who weighed something like 140 (maybe 125?) pounds or less. I was always above whatever that YMCA weight limit was and had to wear a sticker on my helmet. I blocked plenty of guys who were bigger than I was, but I don't remember squaring up against anyone who was more than, say, 50 or 60 pounds bigger than what would have been a 97th percentile sized boy. This kid in Texas is more than 100 pounds bigger than the 97th percentile kids.