Difficulties Installing ABS Headliner in 73 Swinger

Hey guys, I could use advice on installing the pre-covered ABS headliner in my 73 Swinger. As far as I know the car originally had a cardboard headliner (non-bow style) and I’m running into some troubles with the one I purchased. I’ve since seen 72bluNblu’s suggestion to buy one that’s uncovered because trimming is required, but too late for that now.

I started by opening up the holes for the seat belt anchors and for the sun visors, and I marked the location for the rear view mirror (there wasn’t even a hole cut for that) and the dome light area seems to line up properly. What I’m struggling with is the amount of material that extends over the side edges.
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It’s making it so that the A-pillar trim isn’t able to push up far enough
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And the trim that runs along the top edge down to the base of the C-pillar has no chance at all of attaching
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The driver’s side has about the same amount of overhang, so it’s not like I have the headliner shifted over to one side.

I already started pealing back the liner material and marking where I think it needs to be trimmed to. I’m just looking for some reassurance here that I’m doing the right thing by trimming it back, because once I cut it, there’s no going back, and figuring in shipping I already dropped $300 on this ill fitting thing.

So basically I want to cut it to come flush with this edge, and then the trim will be able to be pushed into place?
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The only other option would be to trim it back even further so that it butts up to the trim, but I don’t see how to get it just right so it doesn’t leave a gap at some points. Any help here would be appreciated.
I'll be watching closely. Want to do the same thing.