How original is the car, and which carb came on it (AVS or Holley) originally ?
Is the fuel line modified to adapt the current Holley ? That's a clue.
I replaced the original AVS on my '68 with the Edelbrock 650cfm AVS2.
Really nice carb, leaned out the metering rods 2 steps and it's better than the 53-year-old AVS.
Some guys prefer Holleys, which I use on the racecar & hot street stuff.
I personally dislike the Demons that mimic Holley 4150s, but some guys like their street carbs.
Pretty much any carb change will mean fiddling with connections, so maybe yours just needs some attention.