I had an idea of something like this to fatten up the chorus...
(of course, having a nice voice would have been a bonus, but hey - you get the idea!)

Obviously, some chorus and reverb and stuff would be required on the BVs - then push them further to the back of the mix...


I'd probably drop the "Casey's not coming home again" line too in the harmony, and then come back in on the "...forever gone away"