Reason for this post.............was the manifold opened too much?

My 55 Thunderbird has a stock 292 with a Holley electric fuel pump (measured 5.5 pounds of pressure), manifold vacuum is 20

I took my new to me B manifold to get the inside blasted since it was filled with rust.  I asked the machine shop to open the ports because my Edlebrock carb secondaries could not fully open.  I showed them a picture that Ted posted on a previous post.   They decided to open the the intake (see picture below) and cut the divider (that runs down the center of the manifold).  They probably removed half of the height of the divider because it was "better"
I can't get the car to "move" when I go to WOT from a dead stop.  The car actually stalls out if I don't start pumping the pedal.  It runs pretty good in all other scenarios (around town, highway), it even works fine from a dead stop "if" I slowly apply the throttle.......


Moved the accelerator pump in all positions
Installed a richer Accel pump nozzle
Floats are set to 7/16" with a 15/16" drop
I've tried 3 additional jet and rod combinations per the tuning guide (one lean and two setting on the rich side) 
Tried different Edelbrock step up springs (per Edelbrock and vac readings I am settling on the silver springs
Initial timing is set to 15 degrees (Ive tried 10 to 20)  Distributor is a CRT
Tried adjusting the vacuum advance with the Allen/set screw and I also tried a limited plate for less vacuum advance
Tried ported and manifold vacuum for vac advance
I disconnected the trans kick down rod for a brief test
There is probably a few other things I can't remember at the moment.................so please ask away



Do you think the manifold "opening" could be causing the problem?   I really do NOT want to do this but today I might put the original manifold back on and use a carb adapter to put the Edelbrock on the 55 intake.... I want to see if the problem is the carb or the manifold