My kids both started with a Sportster .22 with Youth synth stocks and 4x scope. Receivers are the same dimensionally as the SB2 receivers, and the stocks are interchangeable.
My son at 9 found it perfect, my daughter at 14 graduated to an adult stock.
I put a 357 together for the kids. Tested it on a nephew with straight wood stock off a Topper 20 ga, and peep sight. He's older/taller than my son, but recoil sensitive and he loved it. When scoped, I plan on a Youth synth stock for my son (now 10) so that it feels like the 22 Sportster he's already used to. (Though the 357 barrel will make it slightly heavier.)
I also have a Survivor Stock that is a bit longer than the Youth synth, and a bit shorter than the Adult synth, so as he grows, I'll go with it when the Youth stock gets too short.
If you are gonna scope it, why not just go with the Youth synth and bypass all the cutting and fussing?
Cheers
Kerry