Here's some facts about left handed rifles.
First,
without getting into all the "Devil's Hand" Baloney....enough left handed rifles, guns and pistols exist; some being very early, to justify the historical provenance of a left handed gun.
1. Early/Mid 18th Century French Trade gun, grave found in Louisiana. (An extremely interesting find !! It raises lots of questions. This gun is featured in Hamilton's book.)
2. HH RisingSon Kentucky Rifle Prior to 1825 Circa 1820....This rifle still exists as far as I know. (A fine example of a pre- 1825 American Longrifle)
3. JP Beck left handed pistol...built as a mirror image of it's mate. As far as I know the pair has been separated...( Did Beck Build this..."Tongue in Cheek"?")
4. Double Guns of all types.
5. Left locked right handed guns
6. Late "Ohios" with double cheeks (right and left side...as far I I know these are right handed rifles with a cheek on each side)
Secondly...... Shooting
Not everyone is me! A lot of arguments and even bad advice results from people thinking everyone on earth is just like them.
I an a left eye dominate left handed shooter....Primarily
I have the ability to switch to right eye, right hand shooting if I have too.
Not everyone can do this!!
I can switch hit. I have found this to be useful in the following situations....In the military Musket line....I operate through the drill right handed.
In hunting, I shoot left most of the time unless I can only shoot right....so I practice both ways.
I prefer right handed guns...I just do.
If I was investing in a full house build, I would recommend a left handed rifle that fit well!
Since I can shoot off either side.....I can shoot my only Left handed gun right handed if need be.
A fine right handed gun (even with cast off) feels good...some very good or at least
comfortably functional off the off side.
What I'm getting at is, I have no qualms about using a fine right handed rifle off the off side. If I found a good deal on a used right handed rifle....I would sure get it.
One of my favorites was a used custom built right handed rifle.
Your results may vary....
Thirdly....
Having one built.
Here's where we get into some trouble....
For whatever ever reason....
if a customer is going to default on a Custom order, that person will be left handed a great majority of the time.
It is what it is.
Maybe some artistic left handers are flighty dreamers?
Many Gunsmiths are reluctant to build a fine left handed rifle, because of the customer defaulting...lack of funds....does not like the gun....ect...ect...ect....
The only people that want a Left Handed Rifle are...left handed (even left handers like myself prefer right handed guns for special historical guns) so a smith cannot sell a left rifle as easily as a right one.
The smith could and many have lost their butt on a Left handed build that was defaulted....
Another reason....There are very few really good left handed locks!!
The Catch 22...For that reason many will not build a left handed gun. Never ever ever....give any gunsmith ( I don't care who it is) all the money up front...never do this!
With that said, Most really good gunsmiths will build a left (Isaac Haines) Jim Chambers kit for you as the Chambers sets are very good reducing labor. Others.....not so much.
In closing....
Left handed guns do exist historically.
If you can shoot a right handed gun well, don't overlook good used right handed customs.
If you desire a certain historical piece, a Bench Copy... a right handed gun may be your only option.
You may have trouble finding a Gunsmith for a high end left gun.
The Jim Chambers Isaac Haines fits your criteria and it is offered in left hand with a Very Good Left Handed Lock.
Most good Gunsmiths will assemble a Chambers kit for You even if they shy away from a full custom.
The Haines makes a beautiful plain rifle.