I try the diskdrive in an A1200 and it wasn't possible to read hd disks -> this depend of the revision of the mobo (for eg. : 1.A can't handle correctly HD drives with HD floppy...)
Internal HD Floppy for A600/A1200/A4000 are Chinon FZ 357, it can read/write DD floppy but some original games with some drive's seek time "protection" fail...
For A500/A500+, it exists some metallic plate spacers to fit "FZ-35x" style drive in place "FB-35x". Not so common, but you can find them in the last A500/A500+ repaired byt Commodore Services.
I think that Micronik made some too.
Modified PC drives are much more sensible to the defects than the old TEAC/Chinon/Citizen drives.
I use a Panasonic JU-257 has main drive to read/write new disk, but i use a Citizen "40"( external) to read my old disks that can't be on the panasonic
