68 Camaro- Chassisworks cage and headliner

[EvilCamaro]

I am in the process of putting a cage into my 68. I don't have a headliner in yet and was wondering how much space between the roof and the loop anyone who has done this left? Also wondering what routes they went with their headliner? I am not a small guy so naturally I want it to be as tight as possible.

Any input is appreciated. Cheers