First, the dissonance you are hearing may be due to pitch bend. Personally, I hate PB (some people like it), so I always tune my reso heads as close to my batter heads as humanly possible.
Second, I totally agree with the coated Emperor / clear Ambasador combo. It will cut down on overring. But I would also recommend trying the modern Vintage Ambassadors. They are warmer than regular coated Ambassadors but not as thumps as Emperors.
And if you really want to bring some thunder, try the modern Vintage Emperors. Awesome, awesome heads.