I bought my stuff from them and after a few runs the bearings looked bad...ended up it was out of balance and the main bores were too tight...had to have it balanced and align honed....I would get it unassembled and have everything checked out before you put it together. I know a guy who bought a shortblock assembled and it started knocking upon initial start up and he found a main cap loose. They did make it right but still had to pull it and haul it to them . Mine was a 540 with a merlin block.