Steve'e pages are offline right now, so I can't show a dimensional comparison, but I did get to ammoguide and compare them, the .243 would make a fine donor barrel, the chamber would need little if any modification, they both have the same dimensions at the shoulder, they don't show the shoulder angle, but they looked the same. Just decide on which barrel you want to use, the 22" or a 24" bull or fluted bull, I'd probably opt for the fluted.
Tim