What size fuel line, what size pickup in the gas tank and fuel pump?
I would make sure that you don't have a fuel volume supply problem at WOT only and go from there.
I've built and raced B and RB motors for a long time in many different cars before finding out the stock fuel lines and pickups won't feed much above 450 HP, some versions of the stock fuel pumps won't feed 400 HP :at WOT in the 1/4 mile whiney:
Have you cleaned out the gas tank, lines and filter? Are using all new fresh fuel?
If not, you should: wrench:
Murphy loves messing with us hotrodders and drag racers
Did you degree the cam or install it straight up? If straight up I would make sure it is installed properly, I seen more than one replacement cam gear be off one tooth and make the cam install retarded instead of correctly
Which makes the motors not run as good as they can when the cam is installed correctly