Oil change after break in???

Going thru this myself right now.
1) there is no modern “flat tappet cam.” That is 100 year old technology. But with that said use an oil with lots of zinc. I like Rotella T 1300 ppm of zinc. Joe Gibbs oil is also good but really expensive. Or a good oil and zinc additive.
2) cam break in procedure after the 20mins break in then change oil and filter. Carefully cut open filter and check for materials like cam bearing lead.
3) drive car for 500 miles to seal rings (more or less dependent on manufacture.
Parts recommendations.)
3) as you drive and engine “loosens up” you need to keep resetting idle. They tend to idle faster as they break in. I’m at 300 miles and I’ve lowered my idle 3 times now.
4) change oil and filter at 500 miles. AgIn check filter for debris.
5) during this process keep an eye on coolant and ps levels. Next change is another 1000miles then what ever you want- good to go.

This is a good guide. Modify as needed. I’m not an expert but have built and driven and raced over 25 long lasting MoPar engines - in my life and I’m 50.
Good luck- Joe