That is a really high OG. Fermentation can be difficult at that level, so you may want to consider dropping the OG. I believe an OG of 1.156 would have a potential alcohol of closer to 21% (assuming you could get a yeast to go that far). Assuming you can get D-47 fermenting at that high OG, fermenting to 14% will only drop your gravity about 106 points, so you'd end up around 1.050. That is really sweet. Dessert meads start at 1.040.