First off welcome.
No down to business, I have not found any stainless mounts rings that come close to the Stainless Pro-hunter or Encore SS barrels. On my stainless barrels I just use matte Warne all steel mounts and Warne rings. They look good and match the Pro-hunter well. As far as scopes, I don't think you can beat the new Nikon Omega scope with the 250 BDC. With 150 gr. or 3 triple 7 pellets or 120 gr. of triple 7 powder and 250 gr. T/C shock wave bonded bullets.
As far as lapping the barrel, I don't see a need for it, I am getting 1 inch groups at 100 yards with my above set up, right out of the box.