do pay attention any time it comes off a lift to make sure the shorter shackle doesn't invert.
careful about new aftermarket springs, as they tend to be taller than factory for some reason.
the 3.4L block will go right in and make use of all the 2.8's accessories/intake/exhaust. if the 2.8L is in good shape, you can leave it too and just focus on the trans. there's a good thread on the 3.4 swap in the link in my signature.
the 360 will need a different all-the-things-everywhere.
I've had leaks that never presented themselves with a garden hose and so I used the baby powder method. sprinkle a little bit i the suspect area and the water will make tracks through it leading back towards the source.
literally anything that can possibly leak HAS leaked for some poor owner at some point in time. all holes should be inspected. the hardest one yet for me was a windshield leak in the upper corner that was dribbling down INSIDE the A-pillar and then dumping out on the floor by the door.
what's the flow rate coming out of the pump? pressure is one thing, but if the system can't maintain enough flow, it'll die. a clogged fuel filter, clogged sock, or a dying pump could do this.