Buy Everything at Once or Piece Together

My opinion is to buy it complete.
Unless you really know what you're doing and looking at, this is the best way.
Make sure it will be 100% useable for the year of car that you are doing.
I would buy a new clutch set up and new bushings to rebuild the linkage unless everything is in perfect shape.
Do a lot of research and make sure it will fit your application 100% and what years interchange.
Even better yet, buy a complete car with all of the parts on it and sell the rest, but those are getting fewer and farther between to buy complete.
Remember, a lot of the time people are passing off their mismatched junk and asking a fortune for it.........