Try dropping down your Total Timing a little. Might want to Lock Out your Distributor too. Carb./Camshaft seems a little small. On my 427 Windsor for comparison =
  1. Total Timing = 28* Locked Out
  2. Pro Systems Carb. = 840 cfm
  3. Soilid Roller Cam Specs. = 252/257 Dur. .683/.685 Lift, and 112 Lobe Separation
  4. Rocker Arm Ratio = 1.7s
Hope this helps!