With the mechanical secondaries, once you floor it all the throttle blades open right up, you lose air velocity and vacuum signal to the carbs and they don't meter fuel properly, worse at low rpm. A higher stall converter and a lighter car with steeper rear gear help offset this problem.

The 440 weiand hi rise tunnel ram is a great intake, works much better on a 440 than on most other engine platforms. It will run great once it's all dialed in and on a 440 those intakes make for a nice driving car, however as stated, you should consider selling those mechanical secondary carbs.