Well, I replaced my headliner, non t top, and it's pretty simple, if you are planning on replacing the headliner, and not just replacing the fabric. Pretty much remove the trim across the front and rear window. Most likely you will need new clips a they tend to break. You will also need to remove the a and b piller trim, and for you, the t top trim, and also the visors. I was able to pull and install the headliner by just loosening the side rear window panels. I got the abs headliner at mikes montes and it turned out very nice. Let me know if you need anything else or help along the way.

i did my 79 malibu a number of years ago.

just got to take all the plastics out. be careful with the rear window moulding if urs is steel they can bend and they r hard to fix. the clips that hold the headliner tend to dry up and break. see if u can get them online or at a bodyshop supply company. be careful not to break the headliner. it is almost like a styrofoam cup type material. if u break it they are aweful hard to replace. i broke mine to much and had to use an eldos and their seatbelt hold downs are different but it really didnt look that bad.

it isnt that difficult just as usual take ur time dont over pull anything. also all the plastic trim tends to dry out after 20yrs hell after 9yrs to!! just be careful with ur screwdriver on the t-top trim. after u take off all the trim everything, if i recall, everything just snaps in place.