You realise the reason your bus engine is stuck will probably also turn out to be a similar 6 minute job, when the garage guy takes the bolt dropped down the back of the flywheel out. Or the washer eaten by the oil pump..
We had the classic at a Volkswoeld show - guy with a Ghia had the engine on show. We suggested he reconnected the dangling wire to one of the carburettors. The owner thanked us then said "All the Ghia, no Idea, that's me!"
he did, not sure I want to admit what it was to be honest.... I maintain it was not my fault on account of me not refitting the offending part myself, but I’ll take the inevitable ribbing. There was a washer lodged under a valve! It had sat in the port and, at some point during turning it over, had moved and stuck itself under a valve. Explains why it would only turn 90% round at the flywheel - the piston was jamming against the valve. very, very, VERY lucky that there was no damage. A slight ding on the head side, but nothing that’s caused issues.
WINNER!! Genuinely, I’ve no idea how it got in there. I labelled all of the nuts, washers, screws etc as they came out and still have the same amount now!
Result? Nothing serious anyway. I've done same but didn't miss the washer, it had been on the stack studs which were barely long enough, I'd even reasoned "eight less things to drop down the carbs"...probably after unknowingly dropping it down there.