One of the big problems with the parts, which unfortunately your worthy project won't address, is that Triumph often changed parts partway though a model year run. The parts book often only reflects the first number, not the change. A good example is the change from BS to UN threadform which started in 68. It seems they used up all the old stocks before changing, so some early 68 bikes have different threads to those on later ones.

68TR6P rebuilt as a C
70 TR6R
73 TR5T