The Low End Mac site shows an MCE drive as compatible with the beige G3. However the pictures on the MCE page show the Blue and white tower but the tech info seems to say that the drive is compatible with any G3 tower. In any case it is a place to start. Here is the link: http://www.mcetech.com/dvdr8xdt-d.html.
Also, here's a link to an older (May, 2000) Macintouch forum that has a number of suggestions: http://www.macintouch.com/g3cdr.html