Currently replacing SS:ToW with SSR is unsupported. It might be a good idea to remedy that. ;)

It's a rewrite. Conversion isn't really possible.

Heck. Let's give it a shot.

I am currently working on a mod that should make that really easy with a config like this here:
https://github.com/BloodyMods/MissingRemapper/blob/9cf76a865fddd19d3940f605be093e961070b458/src/main/kotlin/atm/bloodworkxgaming/missingremapper/MissingRemapper.kt#L47

So far I only have support for Items but I'm planing to add blocks as well. Very experimental at this stage but it I tested it with soulshardstow to reborn and the soulshard item remained the same and kept it's souls in them.