You might want to check out some of the events you intend to shoot at before buying anything. While paper punching is fairly standard, trail walks can be all over the map.
Around here (PNW) the pure paper punchers stick with small to middle calibers. .40, .45 and .50 are popular for most shooting out to 100 yards. Scores are usually based on center of the ball and there's nothing to knock over so large calibers don't have an advantage except perhaps for bucking the wind a bit better. Percussion wins out over flint unless the course of fire dictates flint only. Mostly because its easier to deal with.
Trail walks can vary significantly as to distance, target type and power requirements. While small bores are used, sometimes they don't knock things over that need knocking. They're also a handicap when cutting something like a card or string. On longer steel they might not get a definitive "ring". Squirrel trails have caliber limits (.40 and under). The regular rifle trail you see mostly .45 and up with .50 probably being the most common. Percussion guns tend to be more common than flint, but flint is still well represented, much more so than with the paper punchers. Yeah, it rains out here, but I've watched flinters keep shooting while percussion guns didn't. More a user knowledge thing than a gun thing.
As for me, I shoot either a .54 or .58 flintlock for pretty much everything (trails and paper) except the squirrel trails. Swamped Colerain barrels, 37-38".