I found the previously mentioned Campbell profile shingle kit after a gratifyingly short amount of hunting. Multiple winnowing passes of the supply stash over the years has reduced the height of the pile more than I thought. Apparently some of that pile is psychological. 🙂
In this case, over the years is almost an understatement. I purchased this shingle kit sometime in my teens which makes it on the order of 40 years ago. I am conflicted about how to feel about finally finding a use for it. It is not like I have never constructed a structure in the last four decades but never one in HO that required a shingle roof. Let this be a caution against purchasing materials on vague contingency. Or an exhortation to get out this sort of thing and create a use for it. Take your pick.
On the actual usage, the decades have caused some disarray in the reel and, I presume, some curling and taking a set. The adhesive on the back is still viable but, being a belt and suspenders sort of guy, I used double sided tape to attach it with judicious adhesive activation via water and small brush as required.
Side trimming still in progress but the result is satisfactory but does suggest some general weathering will be required to get things to blend.