Tunnel ram tuning

I have completed my small block powered t-bucket and have been driving it. I am now having an issue with my carbs. I have a pretty big custom cam, with a lot of duration, so I'm sure I dont have the greates signal. I am trying to make 600 cfm vacuum secondary Holley's work. At the moment, other than the idle being a little on the rich side, idle and driveablity are pretty good. The issue comes in at wide open throttle, there just isnt any. I have the QTF adjustable secondary kits installed and have tried to slow the opening way down. It just acts like it goes dead lean, stumbles, spits through the carbs and doesnt really recover until I back out of the throttle. I'm in between getting the secondary metering block conversions and adding the secondary diaphram covers with the balance tubes or calling somebody about some custom carbs. Any and all advice on either would be appreciated. Could I actually be way over carbed and need say a 390 or 450 to speed up the air and improve the signal?
Thanks in advance,
John

just a thought but I would disconnect the little lever at the bottom of the vac canisters to stop the 2ndrys opening. then drive it on the prinarys only and see how it behaves.

Yeah, dual 600's might just be too much depending. You say smallblock, with no specs to speak of. That could be a 273 for all we know, or a 408. Or a 350.

Cam, gears, tire specs will all help, converter stall, trans type, etc. More you tell us more help you might get. Progressive or straight linkage?