I did that mod about 15 years ago. It was a fairly common one at the time. The results were that a drive that didn't show up would now work. At the time there didn't seem to be that many drives around that didn't supply term power. Odds are that you won't need to make the mod. I have both Apple SCSI cards but my preference was the Ramfast SCSI card. It had a jumper for term power.
Computers I have at least 1 of: 128k, 512k, 512ke, Plus, SE, SE/30, Classic, Color Classic, Mac II, IIfx, LC, IIci, Quadras 700, 800, 840AV, 900, PM6100, 6150, 8100, 6500, 7300, 8500, 9150, 9500, 8600, 9600, Beige G3 DT, MT, Server & AIO, B&W G3, Tray loading iMac, Slot loading iMac, eMac, G4 DA, Quicksilver
Mac Portable, Powerbooks: 100,140,145,145B, 160,170,180,190, 520C, 5300,Wallstreet, MacBook Pro
Apple III, Apple II: II, II+, IIe, IIc, IIc+, IIgs