If you already had a 400 in it, then it would be virtually the same engine. Like putting your 400 back in except you'd have more power :Brow: Keep the stock exhaust manifolds and heads, they flow better then the 455's head and exhaust manifolds. Now why would you think they would say its not rebuildable? cylinder wall problems? can you sleeve it? When I rebuild mine I'm boring it out to 430 specs :TU: already have the 430 pistons and rods. Just waiting for more of that green paper the machine shop seems so fond of...
