would it be possible to implement cubic chunks 1.12 to 1.17+ Anvil conversion?

[ShinyJustyZ]

We run a server and need to update to 1.18. Our current server runs on cubic chunks 1.12.2, and trying conversion to Anvil results in places being cut off at y=0
Is there a way for 1.17+ (where the minimum y level is -64) conversion to be possible?

[ShinyJustyZ]

There is an unofficial convertor available: https://github.com/BTEUK/CC-1.18.2-Converter

[Niko-sk2x]

The main issue there is columns that would be incomplete after conversion, otherwise it is possible to do this