Nice! Rust free is always good.

Weatherstrip kit should be mostly the same since you have the full door fraames (for the doors) as equivalent year p/u trucks. I got my kit off ebay, it was a Precision brand, and did the job, though the fuzzies (cat whiskers) leave a little to be disired, but the '78 takes a different type, so may be fine. The 78 is straight, my 85 (81 up) have a curve at the back part of the opening, and the manufacturing of the curved part leaves a little room for improvement.

On the door seal, I am having a problem in that the replacement seals are making the doors hard to close completely, being differently made from the originals, which I believe will be the same as your 78, they glue to the pinchweld, and the replacements push on over the pinch weld, this is making things too snug, and the doors must be slammed hard ... still working on that.

There are other brands of seal kits ...