thermoquad help

You said the carb looks clean but did you take it apart to 'confirm' the condition of the O rings, accelerator pump/check valve for the pump well(cover)and what 2ndary jets the carb has?

Also be sure the choke pull-off is not leaking and the front vent stack should be open at the top and not capped. The primary jets are ok, although a size or two large but you have a lean condition for some reason. The choke pull-off vacuum hose needs to be attached to the base port on the passenger side rear port.

What style of carb to intake gasket did you use? If it is a Quadra Jet style, it will cause problems on your 850 cfm T.Q.