My thoughts are you simply can't go wrong with H-4895. Why, because you can start with a 125-130gr bullet at around 36'ish grains and work it all the way up to the top end listed load in the standard load data for that weight bullet. It gives you a very wide range of loads in which none really have a lot of recoil.
I used the reduced loads for my oldest grandson when he was 3 shooting my Ruger Compact and 125gr bullets. At the time he wasn't much bigger than the rifle,
That said the fit of the rifle is just as or more important than the loads he will be shooting. If he can get up on it good and snug, it will be easier for him to shoot and he will notice less of the recoil than if he is stretching to be able to get a full sight picture in the scope. This was him checking his target, when he was actually shooting it was still a bit long for him but it was the shortest stocked rifle I had, and he is a stubborn red headed kid.
He practiced with it all spring and summer and two weeks before his 4th birthday hit paydirt on his first hog, a one shot drop at 55yds.
If your planning on hunting deer I highly suggest looking into the 130gr bullets, or is you go with the 125's get some of the Accubonds, and be done with it. Just bear in mind that most of the lighter weight 30 cal bullets are more or less for varmints, and even though your velocity will be down, we had one bad experience with the 125gr BT and dropped it from our choices almost immediately. The second and final nail was when he shot a young coyote at about 150yds and hit it broadside and did not get full penetration. I had the hide tanned for him and asked the taxidermist to tell me what the bullet did. He said it never made it to the offside lung and had blew up just inside the onside.
I switched to the Barnes 130gr TTSX and never looked back. Of course the boy was getting more and more capable as well and the charges were bumped up accordingly. He was shooting factory 150gr loads when he was 9 and not having any issues what so ever with them.
One last thing, you might also look into picking up one of the extended eye relief scopes as well. This will give them a better sight picture as well as allow them to have a bit more room between the scope and his eye. Just a little more forgiving thats all.