B.W.
We have a Sunshine Kids Monterey high back for our 8yr old who is also 65lbs. He's tall and lanky though, he's 53" tall. THe Monterey has an adjustable shoulder area to accomidate taller older kids, the sides expand. Plus the bottom is wider. Its a GREAt seat and we love it! It fits both our 8yr old (65lbs 53" tall) and our almost 5yr old (43" tall and 45lbs) perfectly. Although our youngest is still in a harness full time.