First...Welcome to ECN from one of the "Jersey Guys"!!
Based on 314 and reference back to 312.6(a) for the removable cover, you got it.
That said, think about the actual layout you intend. The 8" depth may be a battle with the 600s, as the 36" side to side space. Keep in mind the result of the 314/312 calcs is the 'code minimum', and not the "ultimate" answer.
You may decide on a 40" or 48" x 12" box.....think ease of install, possible labor savings, and 'for sure' code compliance.
