As already said use a battery charger when testing and repeat the first test with the throttle opened and then warm the motor up (get it HOT, not barely warm ) and do it again, you may be pleasantly surprised with the differences
What do you know about this motor? Was it rebuilt or is it is a stock motor with a lot of miles on it?
BTW,#7 is the leanest cylinder usually on most V8 with that have the firing order when #5 cylinder fires 90 degree before #7, especially on single plane single four barrel intake manifolds, not so much on stock Mopar intakes
Let us know your results