Good luck on the stock ruger 10/22 reciever but google 10/22 recievers and several will come up probable starting with no-dak, razor, TS and on and on. Try at rimfirecentral . There are a bunch of barrels threaded barrels too and the problem is finding the barrel in your price range.. Most ever one that makes a 10/22 barrel also offers threaded options. Google first and see what you find.
I've seen a lot of people asking about 18.5" barrels after Red Jacket started selling their 10/22 stock (it requires 18.5" barrel to meet federal requirements). There's not a lot out there for the .920 diameter barrels that are 18.5" long. There are tons of 16" threaded barrels but then you go to 19" and 20". If you could go to 20", I'd go with a Whistle Pig barrel.