Skip the Cake Hotline and call GF Private Dining directly at 407-824-1951. First, tell her that you were married at WDW (that seems to help), that you want a 6-inch replica of the top layer of your cake, and that it was the Mickey's Delight style. She can pull your BEO if she needs to, but that style is pretty common. If that goes well, then mention that you'd prefer to have it delivered to Ohana.
If for some reason you meet with resistance, you can always order your cake from the Contemporary (via Private Dining) and have them deliver it to Ohana. They seem more willing to do this, and they will know how to do a Mickey's Delight cake. The only catch there is that usually they make you order an 8-inch cake. Someone mentioned getting a 6-inch cake from them recently, though, so perhaps that policy has changed.
Good luck!
When I ordered the original penguin Christmas cake from Brian, I did everything with him over email and was quoted $100. Then he asked me to phone the order in to private dining, and someone else took it down. It doesn't matter how you contact him, but the more info you can give him about what you want, the more accurate your quote will be. If $150 is too steep, ask him what he can do with a $100 budget.