Are you asking for mod compatibility?
Sort of, but technically no? Read and you'll understand.

Is your feature request related to a problem? Please describe.
When using Cubic Chunks, if I die below Y=1, the grave spawns at Y=8ish.

Describe the solution you'd like
Add a config option to allow the grave to attempt to spawn below Y=1. I'm not sure if it will allow it to work properly with Cubic Chunks, but without that setting I can't even test if it does.

Additional context
If necessary, Cubic Chunks does have an API. Though I'm not sure how useful it would be if this mod works fine below Y=1. If it does work below Y=1 without additional support for Cubic Chunks, then this isn't really compatibility just an additional config option.