I agree with Mauser06. I think perhaps the best course of action would be to go ahead and sell your current rifle, and then order just what you want.
You already have X amount of money invested in the current gun. I hazard to guess that a good maker will charge you as much to restock that gun as build one from scratch. Even then, the resulting gun will be a compromise. The existing lugs, sights, etc. will be a sticking point for the builder that limits what he can do. Also, I think it will be harder for the builder to work around items like the lugs than if he can install them where he needs them.
Unless those parts are sentimental, like your dad built the original gun, I think the effort will not be worth the time and money.
I believe I recall that you got this rifle, and it did not come out quite like you wanted. I am afraid that this will be the case even if you get it restocked.
Again, I would sell it, and have a new one built. I liken it to guys who ask about swapping a V8 into a 6 cylinder Camaro. The best monetary advice is always to sell the V6 Camaro, and buy a V8 Camaro.
I hope this helps a bit. God Bless, Marc