You might want to consider a Savage. I’ve started a son out deer hunting with a Savage chambered in .243, it was a model 110 and worked out very nicely. One nice thing about the Savage is that your not going to get all worked up about a few hunting dings that are put in the rifle over the years. Something else to consider if you choose to cut down the stock, a new Savage stock isn't ’going to break the bank.
I’m a big fan of the .243 for deer but I do know there is quite a few that think it runs a bit on the light side. The 270 is an outstanding round, you might want to consider the 7mm08 as well.
Good luck and please let us know how it goes.
Oh and I’m not a big youth gun kinda guy. They do grow up REALLY FAST