I'm going to say do it your self. I did and if I can, anyone can.
The guys/gals here will help you with every step. The brakes can be bought from a vendor or out of the "parts for sale" section or gotten at a salvage yard. The P/S system can be bought from a vendor or eBay or out of the "parts for sale" section.
First, decide what P/S system you want then decide on what disc brake system you want. Each has it's ups and downs IMO.
I just finished the "All Ford" disk conversion and it's GREAT. I also just replaces all parts of the steering on my 74 and it drives like a dream now.
Tim