Yeah, a good dry sump pump these days should be able to pull up to 20" or more depending on how fast you want to spin it. My new Peterson pump will pull more than 15" when I'm running at 50% of crank speed.
As for the other debate, if the rings package is designed to work with a crankcase vacuum then running the engine without a vacuum will drop the HP a bunch. That is just the way the engine is designed and it doesn't mean that the engine is built wrong. Super narrow rings need the help from crankcase vacuum to seal. That is why a Pro class engine will lose 50 hp if you put a breather on the valve cover. Those engines are designed to be run sealed up with a pan vacuum.
