QuickFuel 880 Surging/Missing At Wide Open Throttle

Hello All. I bought the Quickfuel SS-880-VS to replace the Holley 770 and put it on my bored 30 over 440 with Eddy dual plane, headers, stock heads, RV purple cam, not sure of lift/duration but its not overly aggressive. Fuel/Air at 11, initial timing at 16 deg. 5-6 psi fuel pressure. 3.73 gears with 727 Auto with shift kit and 2700 stall. I am running a Mopar Electronic ignition and orange box that's only 2 years old. This is in a 69 Barracuda notch. The carb came with primary 80, secondary 86 and power valve 6.5. I am in Alberta Canada at 3000 ft above sea level. Initially, out of the box the engine started and idled fine but when I was driving it and went to punch it, it would die and flood out. The speedshop that sold it to me supplied me with 78's and 84's so I put the 78 in prim and 84 in secondary. After doing this it would barely start and would backfire through the exhaust. Very loud bang. Thinking a lean condition, I put the primary back to 80 and kept secondary at 84. Started fine, idled well while driving and at WOT it pulled hard but seemed to be missing/surging slightly on the way up to WOT. Thinking a little lean on the secondary side I put the 85's in the secondary but now seems very sluggish. Now I'm not sure which way to go from here. I swapped out the Champ RJ12YC's and put on new MSD wires as they were needed and hoping if an ignition thing it would clear up. I wondered about the power valve but when talking to Quickfuel they said they just change when it opens , not how much it flows. They said that the power valve channel restrictions would need to be changed to larger size to increase the fuel flow. Really?.......Do I have to go to all this with a new carb?
If anyone has dealt with surging/missing at WOT and found a fix, I would love to hear your story so I can give it a try. Appreciate the help.