I'm doing the exact same thing now with your cars' twin except parting it out as know one wanted it at the time. Even if the block is scrap a standard bore 273 should be easy to find and then you can reuse your pistons and maybe cam all the good stuff is forged. Most people aren't huge 273 fans except a few of us old guys that know them so that is in your favor for a bargain basement price. In reality you would be better off buying a whole block then shopping for pistons if it does come to that. I wouldn't be suprised if a few members have 273's they don't want and will never use.