If you don't have PCI slots on your clone, then there is no hope to put USB on your Mac, but if you do have PCI slots on your clone, then you can put a USB card on it and should be able to use all the new USB goodies.
If you don't or can't put USB ports on your computer, then I would start looking for older series Epson printers, such as the 740 that have standard 8-pin serial. I would also look on eBay for older peripherals that work on serial.
One last ditch effort is to purchase printers that can use Ethernet and Appletalk and connect to them with that connection. You can purchase a new Epson and for another $150, purchase a full Ethernet adapter for the Epson. The adapter is an Axis 1440 print server.