Taping drywall of different thickness
With uneven work like that you will have to build up the sheetrock side I use a wide mud knife at least 12" when trying to cover uneven areas, as far as the kind of tape paper or fiberglass I use both but preferr fiberglass in this case as it helps reduce cracking. Also I would not do in 1 coat but use several thinner layers. For areas like this I will use "hot mud" because it sets quickly and in some cases as soon as the first layer is complete the starting area is dry just don't mix two much up or you may have a mud tray that turns into a brick before you get done. The last caution is hot mud is tough to sand so I will put my base coats on then a thin layer of topping mud very easy to sand but it takes a day to dry.