in dire need of some 68 Barracuda parts

Hello David,
Welcome to the site. There are indeed many knowledgable (and helpful) people who hang out here. I'll contribute a small part here and I'm sure there will be others who can add much more info.
I owned a '68 ragtop for 4 years until I foolishly priced it last summer. I really liked that car. I put 20,*** miles on it during the time I owned it. It was one of the best older cars I've owned and I drive old cars all the time.

1. Upper and lower trim is reproduced but kind of expensive. The two pieces look very similar but are different. I believe there was a thread on here showing the differences.
2.I'm not sure whether this is reproduced but I think you can find an aftermarket trim that will work decently. I would check with a windshield company. They might know of something that would work off of a later model vehicle. (I'm thinking 70s or 80s truck.)
3.Knobs, used. Gauge covers can be polished.
4.Should be fairly easy to find used.
5.I think the ash trays are 'vert only but I'm not sure.
6.Arm rests are definately 'vert specific. Dart may be the same but I'm not positive.
7.Most seem to be pitted to some degree.
8.Dash pads are '68 only so your choices are pretty limited.
9. Might find something off of a later model you can use.

If you don't want to spring for the high dollar new stuff you just have to be patient and pick up a piece here and there as you find it. I search the ad section here on this board and ebay. If you are patient you can usually find what you need.
Good luck,
Dallas