I agree. A tamer cam would have netted you 20+ mpg's for sure.
Crap! I got 20 mpg's out of my '79 Magnum with a 360/904/2.76
Factory 4bbl. 625 Fed-Mougal AFB, MSD triggering a factory distributor, & dual exhaust @ 2-1/4. With twin cats I have to ad.
(Couldn't get around the law of the time.)The car loaded with fuel was over 4K in weight.