I don't know how different the headliner in my '38 is from your '41, but I used a 1-piece fiberglass headliner. I figured the fiberboard might be kind of difficult to do by myself, so I opted for the fiberglass. It required some trimming, and a fair amount of trial and error. I didn't want to make the mistake of trimming too much, so I did a little at a time and kept trying it until it fit. I brushed on some brown paint once I was done trimming, and am happy with the result.
