Carb for 383 4bbl

Thanks - helpful! Seems like a rebuild is in my future here.

There is an old adage: "Ninety percent of all carburetor problems are electrical." Therefore, you may want to check your timing, and if yer running points, you should replace them (and the condenser) with a USA-made set. Ray at @halifaxhops can help you with good NOS / NORS parts. All the current point sets and condensers are Chinese crap.
Is there a tight bend in the rubber hose between the frame and the fuel pump? I so, the hose can collapse at the bend when the fuel pump is working hard to supply the demands of the engine under acceleration.

How's the fuel pump pushrod? A worn one will diminish the efficiency of the fuel pump.

FWIW, I still have the original AVS on my 375 hp '68 440. It's had a couple of cleaning and gasket replacement sessions in the 120,000+ miles I've put on the car since I bought it in '68 and it still runs well.