Oh Glenn, pissing myself laughing. Memories of something very similar.
Years ago we were building a L20b for the rally car. Can you imagine three guys rebuilding the block & head only to drop a bolt down the front listening to it tinkling down into the middle of the engine. Then to see the three of us pick it up and shaking it, turning it upside down etc. Ended up having to dismantle it. So at 2am we had managed to rebuild, dismantle and rebuild it again. Then it wouldn't start because of the compression. Easy, tow it behind another car and dump the clutch. Was a top engine though.