I suspect part of the problem is that without any push rods between followers and valves, the valves don't open and close as they are supposed to. As a result, you have "compression" in all 8.
Hahaha, that made me chuckle. I certainly remember to close the aluminium top tailgate required a firm push on the centre handle and an equally firm hand on the bottom right corner, glad I don't have to do that any more.
Wow, handbags at dawn!
The ignition system on these things is not complex.
The common culprits for no spark seem to have been discounted. Because there is fuel it can't be the ignition amplifier. Because it runs it isn't distributor, rotor arm...
I believe the EGR valves are different as is the emissions control. Pre 7A vin EGR's can be blanked without a software patch but after that vin, you need the patch.