technically you dont NEED a manual box. but otherwise yes that is all you should need.
you can do it the way i did it which is rip the pump and lines out, drain all the fluid form the steering box and just look the 2 ports together. the ratio wont be the best in the world but it will work just fine
Most power steering boxes are 16:1 ratio and most manual boxes are 19:1 for better leverage. Find the letters stamped on the little tag on the steering box and look it up online to find which you have. If it's 16:1, then look for a 19:1 for easier steering. Often the manual cars had slightly larger steering wheels also.
By far the most important part of conversion is the alignment. A manual setup with PS alignment is a b!tch to park. A correct alignment lets you steer much easier with no muscle. Remember, people of all ages and sizes had to be able to drive them, including Grannys. Finding a shop that knows how to do a good alignment on a classic can be tough. Check with local car clubs for info.
i converted my 68 t to manual and kept the power steering box. i removed the pump and took the slave cylinder and control valve off the centerlink. then i installed one of those power to manual conversions studs on the end of the centerlink.
if you do not mind strong arming it the power to manual conversion stud is the way to go. i just put manual steering in my 69 cyclone, you need the box, pitman arm, idler arm and center link to do it like stock.
I did that NASCAR conversion before. It sucks!... (IMHO) With the PS box ratio and a heavy Torino, you will not be happy if you drive the car often. Now I just suck it up and rebuild the control valve. Maybe on a Mustang it's not as bad.
Not sure what you're budget or goal is with this project. If you want to keep the power steering w/o the mess of the stock arrangement - Borgeson does make a steering box with integrated power support - meaning the power assist lines run right into the steering box, it does not use the external ram.
I have the setup on my Ranchero and love it. Works very nice.
If you want to get rid of the power steering completely - just follow what others have suggested here - that works too.