I usually leave the hood on, have them both bolted together, have the car on 4 jack stands, but taller than 6/8 inches. I'm fatter than that. A floor jack to raise the back of the trans as you slide the assembly together. And sometimes it is easier to leave the engine mounts off untill you get the trans crossmember into place. Also I leave the pullies off, and on a big block I leave the water pump housing off. But have the tranny lines laying in place as with the headers going in around the same time as lowering.