info on my 69 chevelle POST 300 deluxe?

I have a 69 chevelle that is in need of some love. All origional with 70,000miles on it I took the 2 speed power glide and 250 straight 6 out of it and will be replacing it with a vortec 350 and 350 turbo tranny. Do i have to change the drive line? and what reason did chevy have for making a 2dr. Post in 69 with a 6cyl. in it? Any advice will be happily taken. This will be my first rebuild of a chevelle, but not the last lol. It has factory ajustable coil-overs and sway bars that I thought only came on the V-8 cars..... I also need a new driver door and driver fender so if there is anyone out there with there pics of a 2dr. post 300 deluxe please would you let me see them or if you have any extra parts that you want to part with......... Thanx guys