5800 rpm issue
I know this maybe sound stupid, are you sure you have enough carb to hood clearance. It maybe starving for air. We had a deal in a 66 chevelle with a dominator carb and intake install, it ran fine with the hood off. We took it to the track and it fell on its face.We removed the hood and it ran fine. We ended putting a cowl hood on the car and some fine tuning with jets and timing but it clearly had a problem with the old stock hood. Not trying to be an Az.. but is the clearance OK for air intake ?
JMO