Low compression

[Lynn Eades]

Malcolm, I don't think there is enough room to get the heads off with the lower rails still in place.
You will have to lift the head 1 5/8" to clear the outer studs, but higher to come off the center (2 3/8") and top (inner) studs (2 1/2")
Bearing in mind that you can probably roll the head "out" to get off the higher studs earlier (if you follow) but you would need to be lifting the head "square" from the deck, for say 2 1/4".
I don't have a carrier with an engine in it, but don't think that is possible.
It would be good if someone else chimes in (in case I am telling porkies)

In your current situation, maybe a re read of Robs advice is a good move?