About options
Option # 1 : Over Easy II, DB25 adapter /20USD
OverEasyII is an adapter that converts BlueSCSI 1.1a Desktop to DB25. 
*It can also be installed on 1.0c. Also, it cannot be installed on models with uneven cases such as Color Classic. In that case, please purchase 1.1a DB25.
 
Option # 2: OS pre-installed MicroSD card /10 USD
SD card with Mac boot system installed. Formatted with exFAT, you can choose System 7.1 or 7.5.
 
** Highly recommended **
Option # 3: Beezul-bulb , Bi-color LED controller with Red&Green LED /5 USD
Beezul-bulb is a small PCB that controls the Bi-color LED by Satanic Mac Club. Includes bracket ring, Bi-color LED (red-green) and cable. Can be installed on Macs with all HD access LEDs.
Wiring instructions here
* The bracket ring can be used for SE, SE/30 etc., but please note that there is more play than the genuine one.
 
About BlueSCSI
Blue SCSI is a small device for SCSI hard disks that uses an SD card. This product is a genuine product licensed by Eric Helgeson.
https://scsi.blue
BlueSCSI is an open source, open hardware, and open design SCSI solution for vintage computers. It is built by the community of creators, not knockoffs or cloners. Please note that sellers who are not listed in the above link will be deleted above.
https://github.com/erichelgeson/bluescsiOur Blue SCSI is manufactured under the same conditions as other distributors, the only difference is Made in Japan. Soldered by a craftsman who has been soldering for 30 years, inspections were performed three times after the program, after soldering the pin header, and after completion.
 
How Blue SCSI Works
It is a reliable and reasonable method to solve the difficulty of obtaining used hard disks, which is a weak point of 68K Mac. It operates with low power consumption and can operate only with SCSI bus power. It is also recommended for models with insufficient current in expansion cards. The speed is faster than SCSI2 SD v5.1, and MacBench2 gives a score of about 180 when Quadra605 is 100 (* measured at LC475 68040 / 40MHz).
 
BlueSCSI is not a method like SCSI2SD, but uses a MicroSD card with the extension HDA disk image file. When backing up with the current PC, it is convenient because it can be handled as one file. A maximum of 7 volumes can be mounted on the disk image, but since SCSI-ID is assigned, it is assigned to a SCSI-recognizable ID (0 to 6 * Old Mac 7 is used by the SCSI bus controller and cannot be used).
 
Confirmed compatible models: SE / 30, Classic, Classic II, IIci, Color Classic (II), LC I / II / III, LC 475, LC 575, PM 6100
 
Conditional operating model:
Plus (* 1), IIsi (* 1), SE (* 2)
 
* 1 External power supply required (via USB or FDD power supply 4-pin connection), PLUS can install a non-mounted diode on the logic board and supply 5V to the SCSI connector.
* 2 Incompatible chipsets are assembled in some lots.
 
In addition, it can be recognized / mounted by G4 of a machine equipped with a SCSI card. I don't feel it is necessary as a boot disk, but it is convenient for data migration from the current PC to 68K. Some models other than the above can be used and some are not. We guarantee only confirmed models.
 
Product Summary
Blue SCSI board and mounter set. The only other thing to prepare is a MicroSD card. Class 10 8GB is recommended. Format with exFat or FAT32 MBR, and after formatting, place the HDA format disk image file in the root directory of the SD card. At this time, the file name should be "HD50_512.hda". "HD" is recognized as a hard disk when viewed from Blue SCSI, the next "50" is the SCSI-ID at the beginning of the second digit, and any number from 0 to 6 is placed, and the first digit 0 is SCSI-LAN. -ID is usually set to 0. Next to the underscore, "512" is the sector size.
The completed file can be edited with an emulator such as Sheep Shaver. If the environment can start the installer on an actual Mac, the installation work will be done on a Mac.
https://github.com/erichelgeson/BlueSCSI/wiki/Usage
 
Once started, LOG.txt can be created as the root, so you can follow up when an error occurs.
 
The Youtube video below is perfect for a better understanding of Blue SCSI setup with Windows:https://www.youtube.com/watch?v=szXAcwyee9gNotes: The Macintosh version of Basilisk II does not recognize hda files, so you need to use SheepShaver on the newer OSX (OS 11). However, since SheepShaver is a PPC-based emulator, it is not possible to install a 68K OS. Do it on a real Mac. SheepShaver is used only for exchanging HD files or editing the completed hda images.