I was lucky enough to win an auction - that was simply listed "range of old EMU parts". I think the guy worked for the NZ parts distributor here in NZ and he prob wound up with a whole lot of stuff.
I had the E4K and also a EIV in getting repaired recently - I was having a clean up at home and found a box with a smaller box that said "6855" - opened it - and there was the chip that I had been searching on the net for.
Pure luck - I almost biffed the box out!!
Try eBay?