For the front seat springs, you could check at
www.transamcountry.com in the "interior" forum. There's an auto upholsterer there named mrpontiac80 who has made some of those springs and was selling them. He may still have some or know where to get more.
Also, you could do a search there for the leaning seat problem. I do remember someone saying something about replacing a plastic bushing and where to get one that will work. And there are other reasons, like bent or cracked metal sometimes.