Cylinder 1 backfire through intake

78 gm 350 5.7 Cid. 4 bolt main Backfire through intake/carberator.

Rods are good, even compression

New distributor, timing gears/chains, plugs, wires, fuel lines, fuel filter, new edlebrock 650cfm carb, lifter springs don't appear to have any wear (push test). When I disconnect cylinder 1 plug from distributor, I know longer have back fire.

My thoughts are a potential whiped cam lobe on cylinder 1 or a single bad lifter. Lookin for help!