I have a few ATA PCI cards in use on old PCI macs, they are decent even with older HDs (over 20GB, 7200 RPM). Personally I like getting a cheap UWSCSI cards and running a 10K or 15KRPM late model SCSI drive in those machines ( the ones that wont melt down or make too much noise). You can get the SCSI cards cheaper then ATA cards, and those fast SCSI drives are about worthless so they sell for nothing on ebay. For me old Beige macs are more authentic with SCSI, and I don't see the need to spend $$$ for G3/4's faster then 400 or so since you can run OS 9 on cheap G4 towers.

What you do need to look out for is a 7500/8500 loaded up with RAM on ebay selling for nothing (or one parted out) for those hard to find 128MB FPM or EDO DIMMs (also a cheap way of getting the CPU upgrades as well). A few years back I won a 7500 and a massive amount of parts for under $20 (local pickup only). It was a 15 minute drive on the highway but I ended up snagged 5 or so G3 upgrade CPUs, a couple PCI RADEON mac editions, tons of RAM, a few SCSI and ATA cards, stack of original software CDs, external SCSI cdroms, motherboards from 7500/8500/8600 plus power supplies. Filled up my whole trunk.

A Fast HD, plenty of RAM, and a cheap CPU upgrade would make the 7600 fly on System 7/8/9 and not cost that much (unless you are in a hurry).