Major Sights;
There are alot of us here on CGN that have been down the screw in choke trail more times than we care to admitt we spent money on.
I would strongly suggest you dertermine what your going use this gun for and how much your in love with it.
Separate your wants from your actual needs. You may want screw chokes in a shotgun but do you "really need" them. If your only going to use the gun for partridge and skeet and close in work you will never have the IC or skeet tubes out of it. The others will collect dust. Same situation if you just use it only for ducks, and or pheasants, you will have one set of tubes in there and the rest will sit in your bag.
How do I know all this because I own at least half dozen shotguns that are use specific, and I have little crown royal bags and plastic film containers full of screw in chokes that never see the light of day. But I have them just in case I need them, but in reality I never will.
If your a one shotgun man and going to use it for a bit of everything and your absolutely head over heeels in love with this OU and your getting it for a steal.
Then you might want to spend the big dollars and have good set of tubes installed by a good smith. The fellas posting previously have already stated good tubes installed by a good shop is not cheap, and they are correct.
Hopes this helps put things in perspective.