I had a GAAH top with glass window installed. Very nice fit. I assume you have an S model because you have the headliner. I had to replace the center plastic because it was split, which is mild common issue with the center piece that is directly over your head and holds the headliner. I suggest visiting a few websites with some great DYI subjects.
mikesporscheboxsterwebpages - mikefocke2
Technolab/PedrosGarage: Porsche PPI, Porsche Service, Performance Parts
Also Mike info on replacing the top:
replacingthetop-adiy - mikefocke2
Good Luck...