Carb Help Please

I just had a thought will slant 6 factory line be too small on a v8 360? I upped my fuel pressure to 6.5 pounds. I went out and drove it. If I stomp it just in the primaries it would go like hell for around 5-10 seconds then sputter. If I got back in it right away it'd continue to stumble. As soon as I would stop as if to let the bowl fill up the car would go fine again like a bat out of hell until it would seem to run out of fuel again.