This code includes logic that was used to forcefully drop difficulty after HF and some logic to skip issues caused by that.
Here is Hard Fork datadir, since IBD is broken at the moment.
https://network.hoosat.fi/downloads/mainnet-leveldb-datadir2.zip 75GB
https://network.hoosat.fi/downloads/mainnet-leveldb-datadir2.tar.gz 73GB
https://pepepow.foztor.net/htn/mainnet-leveldb-datadir2.tar.gz 73GB