hmm yes sounds negative , but these are the facts ,the parts just do not fit , but if you are really good with your soldering iron and have really good knowlege about electronics you could if you really think your eMac is that ugly to show anybody make a headless eMac (means without crt in a normal pc case )and use the iMac without its internals as a monitor , connect all ports from the eMac to the back of the iMac job done ...sounds to easy , but i promise you it is far far from easy
but if you could manage that you could have your headless eMac under the desk while on the desk sits your immaculate iMac and nobody will notice that its only a monitor, as you start up the hidden eMac with the iMac's powerswitch and use all the usb , firewire ports on the iMac too because you had extended everything to the iMac