Unless you have a very good deal, the Acard SCSI to Sata adapter are unaffordable. I see them selling for around 250 USD.

I have used an Acard SCSI to IDE adapter with an SSD IDE drive of 8GB, SLC chips, in my Mac IIFx and the thing it bloody fast and silent.

Another option is to keep your SE/30 stock on the inside and add an external SCSI drive of 9GB for example: then you don't have power supply issues while you can use a big drive. I have a few of these and they can be easily swapped around between different Macs.