I literally dealt with this issue last week. My ACS freewheel on one side was catching onto the cone/dust cover. A 1mm spacer didn't work.. it took 2.5mm to clear the cone, thus bringing my chain completely out of alignment. What worked for me was modifying the cone, I took a file and trimmed about 1.5mm off. It was relatively easy, although I wish it wasn't an issue to begin with.

Not all freewheels will have this problem, you need one without a lip that changes the inner diameter.

I'd be interested in a cone/dustcover that works without modification.

OP, please keep us updated.