Great Advice SwampeastMike...I will put my son to work on these items. I have heard the same advice from a lot of Corvette enthusiasts and you laid out the target spots well.

 

Cleaning ALL of the grounds/electrical connectors and replacing ALL of the vacuum hoses were the two best "improvements" I've made to my substantially original, low-mileage '79. The vacuum hose replacement got it starting, running and not smelling (fuel vapor leaks from canister lines) like new. Cleaning the grounds and connections got me nice bright headlamps (without using relays), a strong, quiet HVAC blower, backup lights that are actually useful, and a fuel gauge that stopped dipping every time I applied the brakes.

Actually the freaky fuel gauge problem started after I'd cleaned all of the grounds under the hood and in the cabin. I figured I'd done something stupid until I thought, "What about the ground for the back?"

It also looks like you're lucky in '81 as I don't believe the front turn signal/park lamps are for some unknown/idiotic reason plugged into the main harness via a non weather resistant connected pigtail. After cleaning grounds my blinkers, flashers and parking lights went wacky. I hadn't cleaned those connectors and they're a real pain to get to!

Oh. The engine harness ground is into the starter mounting--it's a long, fine threaded bolt and there's usually plenty of oil down there so it doesn't tend to get rusty

 

Its actually a 7.5 fuse and if you look at the picture above you can barely see it behind the pink wire in the upper left corner next to the flasher. As previously stated not easy to get to.