That’s good info. My custom reamer(not my design) had 215s right at 3.7”. I cant see much if any gains in .040.The factory CA chamber allows a 215 to touch the lands at ~ 3.660" OAL. The factory magazine has plenty of space.
The factory chamber is actually pretty well designed. The 215s feed from the factory magazine perfectly at .020" off. My Ridgeline has also produced several groups in the .1s - .3s out to 330 yards with two different powders. Brass life is decent. I got 7 reloads out of soft Nosler brass with loads pushing the 215 to 2980 fps with RL26 and 2940 fps with H1000. I'm confident that you won't get better performance shelling out the dollars for additional chamber work.