1972 Duster ABS Headliner question

I'm going to be ordering one those for the missile and it my understanding that they are shipped "to be trimmed".
Since I have not seen one yet this is all just my approach. My first question is there a set of holes or something to locate the dome light? if so start there and get a couple of temp screws w/washers in place. the take some small spring clamps and support the areas at the doors. It is supposed to be supported by the rear and front window gaskets, so trim it so that there is about 3/4" overlap and tuck it in. Once you're at that stage get the sail panels and install them over it and mark the edge where they overlap. If it really needs trimming do that. Follow that around the car .
Andrew