the reloading tables show the 460 Rowland to be quite a bit faster. You might try another barrel in that chambering. The standard 460 Rowland uses a 5" barrel with a 2 chamber compensator. You might need to go up 2-4lb over what the 45 Super uses with your 6" barrel/slide combo.
What you have done looks really good. I want to do the same thing to my Para 14-45.