I managed to find some Ultra SCSI HD, with SCA80 connectors. For my surprise, using an adapter I can make them usable on all my Mac's.
Early versions of the Classic Mac OS (prior to 7.5.2) have a 2 GB limit per partition, so higher capacity drives need only be partitioned into multiple 2 GB (or smaller) segments. For Macs running System 7.5.2 through 8.0, the limit is 4 GB (specifically 4,063 MB) per partition, and PCI-based Macs can access up to 2 TB partitions.
The Classic Mac OS can run into problems when run from a partition larger than 8 GB, and on early Macs that support Mac OS X, the boot partition not only needs to be smaller than 8 GB, it must also reside within the first 8 GB of space on the hard drive.
Prior to the Quicksilver Power Mac G4, introduced in Mid 2001, Macs had the 137 GB/128 GiB limitation noted above as detailed in How Big a Hard Drive Can I Put in My PowerPC Mac?. Although Apple doesn’t specify ATA versions in its technical specifications and Quicksilvers are widely reported as having Ultra ATA/66, yet with Mac OS X 10.2 and later, the Quicksilver 2002 supports big drives.