Try going to
http://www.tk421.net/wizardry/wizardry.shtml and then clicking down through the frames to Wiz8 and then Items. Click on the link for 'Gadgets' in the frame that comes up and you'll find the entire gadget list, all of their locations, and what they can be merged with.
This list includes the "phantom" gadgets that no one has been able to find, however, so be you'll want to be aware of that -- no one seems to be able to find the High Voltage Transformer, the Demon Doll, the Electric Eye or the Loudspeaker.