Accidently installed tilapia instead of grouper on nexus 7 wifi 2012 topic

I have a problem installing the grouper based roms now. I accidently installed http://forum.xda-developers.com/show....php?t=2354729 this rom. Now when i try to install a grouper based ROM it shows my device is tilapia and installation fails.

how to get a grouper installed on it?