My 340 getting 6 mpg

I will jump on the timing band wagon. I run a 440, 9:1 Hughes cam, ported heads, MSD pro billet ready to run dizzy - 18° initial/36° all in at 2400 - no vacuum advance and tunnel ram with 1:1 linkage 660 center squirters. I get 13mph on average in the current tune and 3.23 gears (287miles each way to Mopars in the Park, Stillwater, MN each year). I am not sure with the 3.91s as that is usually just for play around locally.