Headliner (again)

[Reeds70]

I know this topic has came up several times, and I feel as though Ive read all/most of the posts out there. I am in the process of making a headliner for my 72....I ordered a kit from classics but dont really like it. And I have made panels, and a console and covered them so I would like to make a headliner and cover it with the same material. My problem is getting the right cut for the board I'm using in the front....I cant seem to get the angle correct and it also seems as though it is more narrow at the front...does this sound correct that it tapers as it nears the front?? Thanks for the help