Welcome ti NitroExpress!

Beautiful rifle.
If you run nitro for black loads, you'll likely find the point of impact to be 6"-8" high. Most folks find this issue with such rifles. The new front sight will take care of this.
Blacking the barrels wouldn't likely affect value, as long as it's done (exactly) as it'd been done 100yrs ago. I'd leave them as-is though, because I highly value the 100yr patina seen here.

Enjoy the rifle
Please let us know how load development goes.
You have cast the chambers and slugged the bores..?
What's rate of twist? Bore and groove? Rifling profile?
Share the details, and take advantage of the store of experience here.

Cheers
Tinker