Rebuild is just as reliable if not more so because you know how it's built. I rebuilt my 350 7 years ago after it spun a bearing and I flog the hell out of it. 3 different cams, 2 different types of heads but same bottom end, still strong.
If the block is ruined go to the junk yards and pull a complete 454. Even in my neck of the woods the local yard has at least two 454 trucks out there in the mud. Tear it down and rebuild it the way you want