Sorry, My fault.....I thought we were talking about a Rochester Quadrajet. I'm not very familiar with the Edelbrock quads. My thought by dropping two jet sizes and using matching rods (.030 less)is you would be leaning both the wide open and cruise mixtures, which would be a good thing at higher elevation. As far as your vacuum readings, what is the needle doing?? Is it steady, or does it jump around or drift back and forth?
My thoughts on the 40+ ignition setting at idle (if in fact it truly is 40)is the cylinder mixture must be burning really slowly, which is why you have to fire it off so soon....Just a thought....