Brett,
I think the 1978 15X8 rims that you show as special edition were really the only rims you could get with the WS6 option. I personally don't like those rims and put the machined edged ones on my 78.
In fact, the copy of the GM bulletin you've put on the site says that the 8" gold cast rims are painted gold, including the ribbed edges.
When I was ordering my center caps, the guy asked me what the wheel code was....his jawed dropped when I said YJ8. He figured I wouldn't know.