The fuel is more likely to be the reason you feel more power.  Ethanol and gasoline don't burn at the same fuel/air mixture - and it requires a bit more E10 for a proper fuel/air mix.  Fuel injected engines can adjust for the difference - carbs can't.  By switching to pure gasoline you have provided a fuel/air ratio that evidently is better in your midrange - and that would indicate your engine is running just a bit lean in the midrange, and you should raise your slide needle to provide a richer fuel mixture.

I do believe the jetting on the stock Savage was most likely set up for pure gasoline....although the later changes in jetting may have been done to adapt for the more available E10.

Your TEV valve may also be more functional with the pure gasoline, and you may notice the back will backfire less on deceleration.

Unfortunately in my area there are no gas stations that offer pure gasoline - except some of the Marina's have it for use in boats.