M-3 upgrades?

[JeepsAndGuns]

Hello everyone, this is my first post here. I have a Benelli M-3 Super 90. I had always wanted one since I first read about them, and the first one I saw I jumped on it quick. (it was the first and last one I have seen) Anyways I would like to upgrade it some. Although it is one of my dream guns (ones I always wanted) it is not in the configuration I want it in. Right now it has the standard stock and rifle sights. What I want is for it to have the pistol grip stock and gost ring sights, and I also would love to have screw in chokes, but I have been told that I cant have that cause none were ever made that way. I was wondering where or IF I could get a barrel for screw in chokes, with the gost ring front sight, then all I would need is the rear sight and have a gunsmith mount it on my reciver. I would like to have factory Benelli parts but I am not sure if I can afford them. I was thinking if mabey I could find some aftermarket sights that look close to the factory benelli ones then that would probably be good enough, but then how do you go about mounting them. Can the factory sights be removed and have it look like it wasnt there? I dont worry about the front one so mutch cause it would be covered by the new one, but the old rear sight is mounted to the barrel, not the reciver, so that poses a problem, removeing it without it looking like crap afterwards. How does it mount to the barrel anyways? Glue, soder, weld, made as part of the barrel? Or what. That might take care of the sight part, but that dont do anything for the choke part. I had looked at a couple of M-1's and they had screw in chokes, and I had a idea that mabey I could mod one of those barrels to fit the M-3. I havent seen one dissassembled, but put together they look just like the M-3, other than the fore grip. So I was thinking tha mabey they are basicly the same with the the only diffrence being the front retaining ring (????correct name for this part???) the M-3 uses this part to lock the foregrip in place for when it switches to auto. (works basicly like the locking lugs on a bolt action) So I was thinking mabey a real good gunsmith could machiene this part on the M-1 barrel (if by some chance they could somewhat interchange) to match the one on the M-3's factory barrel and then I would have a barrel for screw in chokes and gost ring sights, then all I would need is the rear sight and I am done, except for the stock (but that should be easy, as all I would need to do is find one) It would be nice if someone here has a M-1 that they could dissassemble for me and take some measurements for me to compare to my M-3. I have a dig. camera and can take pics of anything you need. Well this has gone on long enough, I'm tired of typing..lol Hope someone can help me. Thanks, --Jared