The 20ga MOD choke will work fine with 3" 1-1/4oz #6 Federal Turkey loads. I purchased a 20ga MOD H&R Topper Jr. Classic NWTF JAKES gun for my son back in the mid 90's. It is a nice little shotgun with camo laminate checkered squire stock. It was the start of the H&R/NEF addiction for me. The first day out in Michigan he floored a Gobbler at 22 yards, and 11 days later he doubled up with me on a couple nice Gobblers at 25 yards down in Missouri.
We had acceptable patterns out to 30 yards, but wanted to keep things under 25 yards. Just make sure you find out what loads it likes and it's maximum effective range. Every gun is an individual, your particular one may be better or worse than the next one. Also make sure the POI is where the POA is, if not you may need a better sight.
We used light loads for practice, then I shot the mag turkey loads to determine max effective range, then he shot a couple at 20 to check POI.
To be honest, I think a MOD choke is better for young hunters, gives them a little lee-way if they get the shakes, and they will.
Good luck!