I am working on an Extreme Orange, Orange muffin recipe and what I have found through all my experimentation is that using juice in baked goods imparts very light to no taste at all, most of the flavor cooks off.
Here are some suggestions;
Cut off the ends of a medium orange, extract the juice and save for something else, and grind the rest of the orange peel/skin in a food processor until finely ground. Add this to your cake recipe. The oils from the orange skin impart intense orange flavor and keep giving off flavor even after baking. Also make sure to add a bit of vanilla extract, because vanilla acts like a flavor enhancer to bring out the orange taste. Surprisingly, I detect no bitterness from the white part. Yummy.
Another way, a less natural, but you are adding it to a mix I guess, is to use 1 packet of Kool-Aid Orange Flavor drink mix to your liquids (stir to combine.) This will also color your cake a pretty orange.
I hope that helps. Experiment and please post your results.