I'd say, right now, either buy a new Petersoli or find an old British made Parker-Hale. The Armi-Sport 1842 Springfield smoothbore is very nice as well.
I know this is an old topic. I thought it might be interesting to see what changes the past few years might have made to the replies.
I also can reply to the comment about the Parker-Hale. it is true the P-H is one of the closest reproductions made with several parts being made from original pattern pieces. BUT...
It is true to the 4th model P1853 which was produce towards the end of or after our War between the states.
To serve as a correct CW weapon, it would (did) require a number of modifications.
The P-H had the 4th model's "Baddeley" barrel bands. Those were replaced with originals. The lock screw guards on the reverse side of the stack are of wrong profile, replaced with originals. The PH lock plate markings are wrong but I chose to keep it for the sake of it's being a P-H and the hammer is not quite right but, stayed with the lock plate. The stock was sanded to a more accurate profile but I fear it is still a little too hefty and refinished in a simple oil finish. The bluing was also redone. The stamps on the breach were replaced with originals as was the stock cartouche. The cone guard chain is correct but, I think it was to begin with. I do not remember. Toilet chains are not right. By the way. The P-H has the originals progressive depth rifling.
Every repro bayonet I tried would not fit. I have an original which was loose. I lined the socket with JB Weld and Ground it to fit. Before you cringe, original bayonet's were a lot cheaper when I got, did this. It is marked to possibly have been in the War but there's no proof to say it was either.
As I recall, I was a bit ahead of the curb in "defarbing" a rifle. For the most part, you got the best you could and that was acceptable as made. There weren't all these people set up to sell you one or do yours. Mine was done by our reenacting unit's Lt. who had previously been with a National Park service living history unit and was a dedicated historian.
I think it about wraps it up.
Here are a few pictures of mine, done in the 1980s.