I have mixed feelings on this. Way back when I did my apprenticeship as a light vehicle mechanic we regularly used to jack up minis, 1100s, 1300s, 1800s and even Princesses under the sump (cast alloy on manual boxes and pretty thick so could take the weight but don't try it on a slusher
) . 1800s and Princesses were big heavy cars around 1250KGs or so and we would regularly lift the entire front end off the ground by a jack under the sump/gearbox.
Nowadays I'd be very hesitant to do anything like this. The engine mountings are designed to handle static loads of 200KGS maximum in a downward, compression mode. To hang three (or more) times this weight off them in tension which they aren't entirely designed to handle might not be such a good idea.
I've lifted my beast (including 200KGs of V6 power plant) on and off trestles several times by putting a chain around the front chassis members which I feel is a much safer bet.
D.