If your classic Mac can get onto a network, any non-host based PostScript enabled printer will work. Easiest solution would be an older LaserJet printer with a JetDirect slot such as a LaserJet III, 4P, 5P, 6P, 4000, 4050, 2300, etc. JetDirect cards are relatively cheap, and you can get one with both LocalTalk and Ethernet support. For a modern printer, I like the Xerox 6600dn.