honestly these days i really think SCSI2SD solutions are the best way to go for old conversion jobs. especially the v6 model which lets you plug in via USB for file transfers, use all SCSI IDs simultaneously, and gives you a ton of configuration options. Ive been using them for a while now in a SCSI chain with my MDD and my old hardware samplers, and I'm going to pick one up for my mother's old Power Mac 6100 that she still uses as a print server. The drive in that thing sounds like a hair dryer almost at this point.
But probably a lot easier (and cheaper) to find than IDE-SCSI solutions. performance is a dream on the older systems even with SCSI-1 thanks to the higher IOPS of SD cards.