I appreciate what you are doing with your son. I did this with my children. The 30-30 will give you better and more choices.
You may not like the choice but you could use some cast bullets. Montanabulletworks.com has some good selections. 1200-1300 is good with cast and the 30-30 was designed using 160-165 gr bullets. You can easily go to 150gr and do well.
What I call a squirrel load will kill deer. Use a 115gr cast with 9.5grs of trailboss. Try it. Then as he gets use to this offer just 1 at a higher velocity or even a heavier bullet.
Let him decide how many or how much.