Hi,
Just to expand on my post earlier.
It's not that I don't think the ghost spied wouldn't be a genetic powerhouse - it's just that I think it would look almost exactly like a spied as only the head has a colour and pattern to be affected.
If I had to pick only one co-dom recessive mix to breed to him I would probably go for POG all the way.
That's assuming your main intrest is to prove the ghost one way or another of course.
dr del