I actually just had to do that this weekend on my 79. There is four rivets that you're going to have to drill out right around the area of the window crank. Before that though you may need to take out the quarter window. If you have to take the glass all the way out to do all this then the quarter window needs to come out there's a Phillips screw on the outside edge and a 7\16 bolt at the bottom of the window.channel and then you tilt it back with the main window glass rolled all the way down. It's a bit tricky probably should put some WD-40 on there to loosen things up so you're not having to pull too hard. I was completely disassembling my doors so I could get them chemically stripped so the quarter glass comes out then the window comes out of the track and then drill the four rivets and then finagle the regulator out of the door opening.
Hope this helps