I had to do a little extra with my engine in my 66 Dart which I think will be very similar to what you will be doing. Here is the link to the company I think most will tell you to use. I bought there mounts and things went together fairly decent. I was not able to get the engine exactly where they claimed it should sit but I worked around that. I also did some mods to the K frame for a little extra support. The company is called Schumacher.
I purchased and installed the TTI Headers so I cant speak to any other header fitment. As for the TTI they were not the easiest to install and because I couldnt get my 360 engine sitting exactly where they claimed it should sit I had to modify slightly some of the tubes. I have manual steering so I dont know if PS would make it any tighter. As for installing them in I found I could put the drivers side on the engine bolted to the k frame but had to install the Passenger side after engine was in. Also on mine the torsion bars go in between some of the header tubes which will make removing a little more time consuming and difficult. But all in all I am happy with them.
I did a spring change to SS springs and relocated the front mounts. Also did a mini tub so I dont know what tire size would fit without the tub. I run 295/50R15.
I used the factory type proportioning valve but may end up going to an adjustable one down the road at some point.
I bought my headliner from one of the venders so I am sure you will be able to find those and seat covers from venders
If you visit my restoration thread you can see much of the work you are asking about I have run into as well as any early A body owners. I think you will run into many if not all of the same issues. This group was a great place to get info during my build which is still going on.
