No not missing anything, but you know how these timing chains/sprockets have several different key slots and timing marks, it's pretty easy for someone too screw up. I know a guy down here put a b/blk together and the valves were hitting the pistons. He then pulled the pistons out and had the valve reliefs cut .100 deeper without even pulling the front cover, they still hit, he then pulled the timing cover and set it right, he now has over .200 valve clearance, so after $200.00 it wasn't funny too him.
Zip.