Linux RAID5 Optimal Chunk Size
At a minimum, you want the chunk size to be a multiple or divisor of the filesystem block size. You've got that.
Everything else is likely to be implementation dependent. Since you're starting from scratch, you should roll your own benchmarks. Instead of creating a 14 TB RAID set, test with just 500 GB from each drive in various chunk sizes. The smaller volume sizes will reduce the amount of time needed to create the volume.
When you find the optimal number for your setup, then create your 14 TB RAID set. Test again to make sure you haven't had a performance degradation.