It all fits. My 65 has a 351c in it, and it had a c6 in it when I bought it. No dents to the tunnel that I was able to find. I can't tell you want crossmember to use however since it had a homemade peice in there when I got it.
IT will fit I just blew my C6 up about a month ago behind my 289. The only problem I had was the headers coming in the trans pan but othere than that it fit in there. It was a pain in the ass to take out but it was worth it.