Congratulations on your purchase!
Mike's advice makes sense to me.
If paper patching or finding a proper bullet is a problem, don't shy away from trying grease groove bullets.
Henry rifling has proven to be quite forgiving for me in single shots, especially in 450 bore.
Also, I vaguely recall seeing an A. Henry with a sight as you describe. A good feature to have on a 450bpe rifle IMO.

Now, let's see it!!