Best to find out which one it is and replace only that, preferably with used one from breakers as they are stupidly expensive:
http://www.torqen.uk/nissan/350z/fuel-ignition/coil-packs/1766-350z-de-nissan-oem-ignition-coil-pack-22448-al61c.html
Now you're talking
Very easy to upgrade, upload the files on FTP and run upgrade script. Nothing to do with MySQL, PHP, not interfering so you can do it now
We'll just wait here patiently
Has Barry got a build thread we can check and come up with a complete answer? We just need to check on the coilovers and the diff... since you mentioned Doris, too...
What's the point, you save £37/year, but what if an accident happens and it's your fault...
I always send my updated list of mods, along with photos of the car when I get quotes or go ahead with the quote.
I reckon over £3k labour cost to make it fit, add spraying, materials cost etc. Good luck with the whole project, let's hope it turns out really good, quick and cheap!