I hope you and your grandson enjoy your Ruger American.
I have a Predator in 308 18". I run it suppressed. I really like it as a knock around, inexpensive, yet very effective rifle. I also chose a Vortex 4-12x50 scope with BDC reticle. I swapped in the AI magazine conversion kit, but you'll be set up well using the Magpuls.
I have plans to get some Anarchy upgrades to bolt, no real rush. But check them out and explore around the site for bolt upgrade options.
https://www.anarchyoutdoors.com/ruge...andle-upgrade/
and bolt fluting if you want to get really fancy
https://adarmscustomrifles.com/produ...luting-package
A friend of mine who has several Ruger Americans in different calibers says to do myself a favor and get a Timney Trigger. Also no real rush for me. I've measured my trigger setting at 4 lbs. 1 oz., it's pretty consistent and crisp to me. You do have to remember, it's not a $10,000 custom rifle.