Wouldn't it be easier to use an earlier version of diskdev_cmds, patch it to default to hfs instead of hfs+, compile it, and then rename it to mkfs.hfs as a separate package?
https://opensource.apple.com/tarballs/diskdev_cmds/ On Gentoo Linux, version 332.14 is still fully supporting HFS. (At least I think so... I'm currently on amd64, not powerpc or powerpc64...) But it's patched. Care to take a look? https://gitweb.gentoo.org/repo/gentoo.git/tree/sys-fs/diskdev_cmds (Patches are in the files directory, https://gitweb.gentoo.org/repo/gentoo.git/tree/sys-fs/diskdev_cmds/files) If Debian uses a newer version of newfs_hfs, it should be easily possible to simply rename the old version to mkfs.hfs und thus keep using it exclusively for HFS (not HFS+). In order to be completely sure, a patch specifically for this to accomplish 1) default to HFS and 2) disable HFS+, for a separate mkfs.hfs, should be the least problematic way. The newer version would remain as newfs_hfs and mkfs.hfsplus. BTW, I currently don't have the time to work on PowerPC. I have 2 G5s (one original from 2002, one Dual-Core from 2005), and I tried Debian on them and Gentoo as well. In their current state they are a mess, and I didn't have the time back then to persue this any longer, but as soon as I have (and I really don't know when), I plan to reactivate them with both Debian and Gentoo. This puts me into a special position, because naturally I would use a semi-manual boot configuration, not a "stock" solution, simply because with Gentoo I have to. But I am not a programmer. I can apply patches, manual configurations, but I cannot write code. I consider myself a "poweruser"... So, if you're annoyed by my input, just ignore me. I'm fine with it. As always, just my 2ยข. Linux User #330250