Depressing Dyno results. Need advise

I ran an 11 second 'Cuda with a 800 Holley on 5/16 line................

It's something else.

So far as needing a DP the two carbs flow essentially the same. Once you get your foot down, that fact that it's a double pumper means nothing

You've either got a fuel restriction---cap, pickup, restricted line, hoses, etc, or not enough pump, or vapor problems

This is assuming that the "dyno guys" are right about it going lean and that it's not also/ or an ignition problem