Peep sights have been around since at least the 16th century (and earlier, so I've been told) but rare as hens teeth for the 18th century, so not period/era correct for a 1760s Woodsrunner. I dunno if it'd be deemed legal in many or any matches, probably considered the same as a rear sight on a smoothbore for smoothbore matches - not allowed.
Got the peep sight from member "Tom A Hawk" on the muzzleloading forum, $83/shipped.