I too am interested in a modern stereo option for my ea81, 1987 Brat. I would like to make the stock stereo compatible with my ipod and think I have found a solution. Here is the link for a wired fm modulator, http://www.circuitcity.com/ccd/howToGetItTab.do?c=1&zip=21201&oid=80974#tabs
radioshack sells an rca to 1/8 adapter to complete the setup. That said, is the stock am/fm setup cabable of having new speakers wired to it that aren't common ground?