318 1/8 time improvement

Reading plugs for me is hard with unleaded gas, and i am certainly no good at it! That said, those look lean to me. That combined with a secondary door opening too soon could definitely give a nice big bog.
However! I would make sure i had as much traction as i could get first! Inconsistent 60fts make tuning for power guesswork.
I would find some cheap wheels (kinda hard to do, if you still have sbp) and some used slicks, and see what happens. The trouble is you have two causes of poor 60 ft's at the same time.