You might try one of hodgdon's youth loads
available here --> http://www.hodgdon.com/data/youth/270win_y.php

with these loads Id limit his shooting to around a 150 yards within that range they should be adequate for deer. I personally would use hodgdon's method of determining a youth load But use a load with a 120 grain bullet and work it up till I was at a velocity around 2800 fps that would give me a little more piece of mind to be comfortable at ranges out to 200 yards.
more info on it here -> http://www.hodgdon.com/data/youth/index.php

good luck hope this helps