390 double pumper vacuum

Yup. Someone has done some witch doctor work on that carburetor. It's a 390 alright, obviously by the tiny venturi. Not only has someone drilled air bypass holes in all four throttle plates, but they also removed all four pressed in high speed air bleeds from the top. It's not junk, but it certainly needs work to operate on anything. Four new throttle plates and new high speed air bleeds at least. I would go ahead and remove the four idle air bleeds and tap all eight holes to accept replaceable air bleeds. That would give you a variety of adjustment there. But then, I would also either modify the existing metering blocks to accept idle fuel restrictors and power valve restrictors, OR get new metering blocks that already have all of that. Either way, that carburetor needs a bit of work and or money thrown at it.