Hi there.
There isn't anything that can be crossed over to lace up with the GG hub. There was a brief mention on here of a CR wheel fitting straight on, im not sure where that post went and the person who posted it never backed up the statement.
However, I know there is a wrecker in NZ who has/had a GG or 2, it may have been Bailey Motorcycles, give them a call and see if they still have the wheels. You will probably have to buy the whole wheel, as they prefer to do that than sell just the rim.