critique this Magnum hop up, swap.

Gregsdart,
Your goal of mid 12s is definitely feasible.
I run 99 block, R/T cast heads (all stock), 9.3:1 comp., Mopar crate cam (501/511 lift), knockoff Air Gap, holley 650, 3000 stall, and 3.55 gears. First time out mid 12s without tuning on street tires shifting around 5500. Point is your combo should definitely be in that window with tuning, and I wouldn't fret over the cam you have should be plenty for the expectation. Plus if not fast enough for ya a gear swap would definitely put you into low, low 12s.