The Laser Writer 4/600 PS will do the job just fine with a Plus or pratically any other older Mac for that matter. If you're just going to be printing text and other simple things then it is not necessary to use ethernet, LocalTalk will be fast enough. LocalTalk only really falls down with large print jobs like high-res photos but I somehow doubt whether you would be doing this with a Plus or SE/30!

As mentioned the LaserWriter 8 driver will works with most of the Apple LaserWriters. The drivers are freely available on the internet these days so it is not difficult to obtain them. Many are included in standard Mac system softare installers as well.