I used hardtop doors in my convertible. The only differences that I knew of and could tell were the side glass and the holes for the wedge that screws on the jamb. Vent windows were exactly the same that I could tell. The side glass isn’t noticeable until you lay a convertible glass on top of a hardtop and then you can see the slight taper difference on the rear edge.
I actually used 70 doors in my 68, so I had the body guy relocate the lock pin hole for me. I do recall a couple other small differences in the glass stops, but nothing major. Door latches for 68 I do recall being different and had to swap over some parts.
Took some time and a lot of trial and error to get all the sealing edges all lined up and sealing well. I had the car so apart that it was basically like starting new between the glass and convertible top alignment. Factory service manual is key to understanding all the adjustments.