I've built an honest 405 HP and 380 TQ with a SBC 305 punched to 310 using essentially the same camshaft along with a Performer RPM intake and a Holley 4776 (600 cfm double pumper) in my old SCCA American Sedan car. My heads were no where near what yours were either as we were limited at the time to 1.84 intake and 1.5 exhaust.
Your AF Ratio has a lot to do with the problems you're having. Frankly, she's running so lean, I am surprized you're not melting spark plugs.. My AF ratios are typically 12.5-12.7 on our racing engines.
The 110 lobe centers will produce reversion with IR manifolds and Webers. Reversion is a bad thing for any carb as it (the carb) simply stops working for a moment as air is forced upwards, into the booster venturis and makes a total mess of the fuel being drawn out of the emulsifier wells.. That's why webers run like total crap with narrow lobe centers at lower rpms.