It is my understanding that most of the Hawken fullstocks were made with solid (not hooked) patent breeches. Since the barrels were less likely to be removed from the stock for cleaning, and barrel wedges would not be removed as often, most did not have escutcheon plates.
Most of the Hawken fullstocks being built now have the "flat to wrist" triggerguards. Mine does. We have somehow convinced ourselves that this is an earlier style, and that fullstocks were all "early," which I don't think is necessarily the case. This J&S halfstock was almost certainly built as a fullstock, and then shortened. Check out the triggerguard:
I believe the John Brown (Mormon pioneer, not the abolitionist) fullstock has a documented purchase date, in St. Louis, of 1845. Apart from its exceptionally large bore, I think it is pretty typical:
Again, you see the "big bow" triggerguard and the circular scroll.
I would also recommend that you look at the original S. Hawken fullstock on the
Historical Arms website. Click that link and you'll go right to it. There are just too many pictures to post here. As an S. Hawken rifle, it would be a little later, and the triggerguard looks different from the two above, but it is not the "flat to wrist" type.
Herb Troester, who posts occasionally on this forum, could probably tell you what parts to order. However, as far as I know, appropriate solid patent breeches are simply unavailable now. Some individual gunmakers may have a few of them saved, but since the Allen Foundry closed, the supply has dried up and is not being replenished. I think even the Don Stith kits have hooked breeches now.
There are people on the forum here who know a lot more about this than I do, but since nobody had responded yet, I thought I would throw in what I believe to be accurate. Also, I am aware that nothing I've said really answers your question about building from a kit or a board, but I hope you find some of it helpful, or at least interesting.
I want to wish you luck on your build, whether it's from a kit or a plank! We'll be wanting to see some pictures as the project gets going, you know...
Best regards,
Notchy Bob