After several months of sitting on a drive, I've finally found the time to drop Rachel's engine out.
Thanks to Frank freeing up a lot of the engine, dropping it out was relatively (though nowhere near completely) trivial. Cunning use of a scissor jack, paired with ropes to steady it axially, let us drop it down and eventually unholy it from the gearbox.
Once separated, I learned just how heavy an engine block is, resorting to rolling it on some tube offsets from my truss, just like the Egyptians did. (Stone blocks were placed on logs and rolled along, with the logs that drop out of the back returned to the front).
An inspection whilst the sump was off showed at least some of the cause of her problems - one of the big ends is now black (not the reddy-gold of the others) and has about 3mm of play!