I also bought a Mossad off GB and really enjoyed it, if yours is anything like mine, just replace all the springs and it'll run like new.
Unfortunately the 'Mossad' is not on the Production list, but since its physically identical to the Witness steel, I would be surprised if anyone hassled you. Although mine came with the firing pin block removed, which is also illegal in Production.
Personally I go back and forth on whether I care if the pistol I'm shooting in Production is technically legal as long as it meets the intent. It seems a little silly that a $2,500 Custom Shadow without a firing pin block is legal for production, but a $300 Witness with the firing pin block removed is not.