You could also try Yogi's Inc. They have pretty competitive prices and are great to deal with. They ship fast, package well, and their people know what they are talking about. They carry some Posies stuff along with other brands that should get you what you need. they are online at <a href="http://www.yogisinc.com" target="_blank">www.yogisinc.com</a> or you can call them toll free at 1-800-373-1937. In your case, I think I would call, because they can answer a lot of your questions better than I can.
I'm not sure about taking out springs from the stock set-up. Sounds like an accident waiting to happen to me. I'd replace them with something that you know will work and will be safe.