I agree with Jim Kibler, but Chambers Late Ketland is probably the closest to that time frame without being modeled on something super rare here. I think it could be made to look later by some file work to the plate and pan. Two other touches that I think might help are a stubby dual-throated cock (they seem to have become popular in the later flint period, but the cheap ones are not graceful) and some flashy engraving based on a lock of the period. Vol. II of Shumway's Muzzleblast articles has some articles on locks over time and pictures of the engraving styles. Those are the only attempts at such a survey/study that I've seen, but it would be a good area for someone to investigate further, as I suspect it is cursory at best. I don't think there is really any option except either making a lock oneself based on the original they are copying or picking the closest available lock and modifying it the best one can.
Please note, I'm not an expert or pretending to be such so these are only opinions, but I have thought about this type of thing quite a bit in relation to flint locks used on Southern rifles, both early and late.