I started with my first full bore deer stalking rifle - 270 Steyr Mannlicher Mod. M. Age 14. I was a stocky child and back then there were few left hand rifles.
Not so sure ,/ keen on light fast bullets. Know placement is critical but things go awry. I had no problems with Normal factory 150grain rounds.
Now, if I was going with a youth rifle, think .25-06 with 130 grain bullets, 270 with 140 grain and 6.5x55 plus .308Win with nominal 145 grain.
It does depend on the size of Brady, terrain/ typical shooting distance say max 150 for a beginner and their physical size / strength. Would not go too light on rifle due to recoil. A good fixed 6x scope is fine. Still like them for under 259-300 yards which even in Scottish Highlands is plenty. In is stalking not long range target shooting