I did mine many years ago. I followed the steps in the '68 Body by Fisher Manual section 13 right down to making the stick spacers discussed in Fig 13-10.

If by two part, you mean the folding top and back curtain with the flexible plastic window? Yes, two parts. Plus a new well material, pads, etc. I found that the tacks they recommended eventually started walking out of the tack strips so I had to re-secure the back bow with a pneumatic staple gun and stainless staples a couple years ago.

Note that there is not a correct well material with the correct '68 insulation available so you have to use what is generally available, the non-insulated well.

That said, I would never do the top again myself. I would have a professional shop do it the next time.