With my hands up (again) I did this to a 400/4 in the mid-80's and due to the amount of engines in breakers- resolved it with a new bottom-end complete. Id actually though Id put a wrong bolt- ie not from the original engine, rather than a mistake- but No, id clearly put the long bolt in the lower LHS and on strating the engine after a rebuild- suddenly there was a huge leak and a noise- then the engine cut..I did mention it once long ago on this Forum- as Ive had my present 400/4 for over 10 years now. Time flys...