Dennis,
I think that barrel is a reasonable facsimile for barrel of that era; the extra 10% verisimilitude will add 5 pounds and 4 inches
. What bothers me is the really quick tapered, small-waisted ones that make the fore-end look like a toothpick. Of the standard modern barrel profiles, "D-weight" (which this may be? it is otherwise rare, esp. in longer lengths) is closest to some originals where I've paid attention, but hardly anyone uses a D-weight in .40 or even .50 cal. these days, as they pretty much did back then. C-weights that I've seen are not bad visually, either, with some visual "heft" but a lot lighter.
For what it is worth, the slightly thinner breech should work to make the taper look less drastic, more like some of the old ones, where you can't really see much change in the first foot or so at all. Sometimes they are so subtle that the look like straight barrels with a flare at the muzzle.