I am trying to put together a 357 maximum project and don't want to pay for a compete custom. I figure the cheapest way to build one on an sb-2 receiver is to buy a complete gun, sell the barrel, and send it in to be re-barreled in .357. I want to be able to sell the original barrel quickly, so which caliber should I buy. I found a new .223 for cheap but don't know if it is a desirable caliber. Any input would be appreciated. Thanks, Sam