The body mounts will differ. This is my 1978 frame with a 74 tub and an 81 hardtop. Had 75 doors but opted to do with the 74 and below doors. Hood is a 71 seam filled in. I call it Heinz 57 ha ha! Wish now I would have kept the later model door as pictured.
You will need roughly 6-8 body mounts from a an earlier frame. I believecruiser solutions sell these new. You will have to drill 4 holes. in the rear crossmember.
You might be able to reuse the front A pillar/cowl mounts if you space up the rest of the truck accordingly by 1/2+ inches. you could merely mount two of these mounts higher on the frame than the factory position of a 77. This would actually be the way to go. You could fab your own with heavy duty square tube. source some off a frame, or buy new and call it a day. This would require the least amount of work and would only leave a slightly higher spacing in the rear to deal with.