Somebody has hinckered with it.
It is probably "original" only as being all TC parts.
Is it safe to shoot? Very likely Yes.
Being a flint lock the most important part right now is the fit of the pan against the barrel, if the pan is snug with no gaps,, so that it will not allow powder to trickle/sneek in between lock and barrel your safe.
bubba.50 and GoodCheer have pointed you in the right direction.
You don't have a breech fitting problem,, you have a "tang" fit problem.
Do a little more research about hooked breech-tang fit either here or elsewhere until your comfortable with making the fix. The thing is when you start changing the tang position you'll have to pay attention to the flash-hole position in relation to the lock's pan too,, don't panic, it's easy enough.
A common way to fix it is to remove the barrel and tang,, then make sure the tang fit's the barrel while both are out of the stock,, then figure out why it's different when they're put in the stock.
Again, if the tang is down - the barrel is snug in the stock - and the lock's pan is against the barrel - I'd shoot it.