What you may choose, will reflect what information you need, and your personal level of experience.
The original Ford factory service manual will cover everything but is quite expensive in hardcopy; cheaper on CD but maybe not as useful when you want to jump around from one page to another looking for an answer or picture.
There is also the "Ford Falcon Six Cylinder Performance Handbook" which covers performance modifications to the same engine as in your car.
There are probably aspects of repair or performance that aren't fully covered in books:
With some processes, technology has changed such that you really need to check with manufacturers as their actual recommendations. One good example is re-boring the cylinders, where now the surface finish is required to be much smoother than 40 years ago, due to better coatings on new piston rings.
Hence, you may find a need for the internet, as well as another book or two! There are a good supply of experts on a site like this, and it's non-commercial.
Regards, Adam.