Chinon FZ-357 is standard density drive, not high density, that is ONLY the A model for the Amiga's
To get your FZ-357 running properly as the internal drive, the following jumpers should be set
DS0, MM, RDY, TTL
DS0 jumper horizontal, MM, RDY & TTL all vertical
The drive might vary in dimension to that of the internal A1200 model, you will need to attach the side mounting bracket and maybe place stiff foam or another material across the back of the drive to secure it against disk insertion with only one mounting screw holding it in the case. Hope that helps

Az