You can safely shoot factory smokeless loads in the Pedersoli made rifle. The extra two inches of barrel may give you another 50 ft/s if shooting black and probably close to that with smokeless. In my opinion, not enough to worry about. It will give a slightly longer sight radius at the expense of added weight. Many opinions one way or the other; both are right, only you can decide. There are many sight manufactures; Montana Vintage Arms, Lee Shaver, Kelly to mention a few. Taylor sells Soule type sights that I think are made by Pedersoli. My guess is the mid-range versions of each will work to 600 yards. I know Montana Vintage Arms sights will, but for the price you’ll pay, I’d certainly talk to someone first.
On another note, you can load black with minimal equipment. Just a decapping tool and priming tool will work. A press is handy to compress the black powder, but if using 777, no compression is necessary. Decap, clean, dry, prime, charge and thumb seat the bullet and you’re ready to go again