There really are no good American made shotguns fit for conversion. There are several good imported shotguns though. You need to find one with double underlugs and a third fastener on it. If it has bushed firing pins and double triggers on it, that is better yet. The only guns that I am aware of that would fit your criteria are a 10 gauge Zabala or a Greener Empire model. Some of the older Richland doubles were also made by Zabala. Some will have a Greener type crossbolt on them and some have what's called a hidden third bite or a Purdy bolt. It slides out of the action as it closes and covers up a rib extension that protrudes from between the barrels and goes through the extractor. Either type is fine for a conversion. You should be able to find a good Zabala ten gauge for around five or six hundred dollars. Many of them will be priced higher than that but you should be able to find one in that price range if you look hard enough. I hope this helps. Bob