Is my 340 Overcarbed? Avg 5-6 MPG

OK I am working through it and think I have it figured out. I installed a spacer back under the carb and put a 2" height filter on for hood clearance. I also put back in the 31 squirter and the green cam which fixed the low end stumble issues. I was still getting some popping from the exhaust so I decided to change the spark plugs out because they looked pretty fouled the last time I had them out. Once I fired her back up it sounded like a different engine and all the A/F ratios went lean all of a sudden so I re adjusted mixtures to get them back. I took it for a spin and there is no more popping from the exhaust. AFR's throughout the entire powerband at steady cruise speed are all bouncing between 13.8-14.2. I think I am as close as I am going to get. Looks like I may have had a fouled plug or heading that way in addition to all the tuning.