It's not going to be easy. But please consider these preparatory steps:
1) Take it one step at-a-time.
2) Raise the vehicle.
3) Don't rush the job. Drive another vehicle while working on this (if possible). If not, then do this semi-project though a long week-end.
4) Replace spark plugs and ignition wires. The #1, #2, #3, and #4 wires must be routed first (to include their location behind the engine mounts), and then finished with their respective terminals at the spark plug.
The right-rear shield requires the starter to be removed. Ouch, I know! But that funky shield that wraps around the oil dipstick can only be accessed that way. Consider removing the front "Y" pipe before attempting. You'll be glad you did.
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The right-front shield is tricky, and requires patience. The plastic duct for the right air cleaner snorkel should be removed to make things more visible and accessible. The bolt that holds the shield is aligned with the top of the engine mount.
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The left-rear shield is the easiest. You're right! From the bottom of the Vette. The oxygen sensor connector gets attached to this shield, so be careful detaching it.
The left-front is the same way as the right-front. Bolt at the edge of the engine mount; however, you'll have to contend with the alternator. So perhaps it would be easier to remove the alternator w/ the bracket at the same time (off the front of the cylinder head).
For the wires, there is a clip at the oil pan for both sides where the front two cylinder wires on either side get held in place. Yes! Below the "V" shield.
Unless you want to go through this pain again, replace the ignition wires. As a said before, route the #1 and #3 wires down from the rear wire support, to the clip at the oil pan, and up behind the engine mounts. This is why you should not trim, cut, and finish the terminals at those cylinder locations before routing.
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GerryLP:cool
p.s. I have some other photos in my share website, These could help you in identifying things.
http://l81power.spaces.live.com/?lc=1033