78 K20 Gas Milage Suggestions

[learyw]

I'm getting 7 mpg on my stock 78 K20, and I already drive like an old man. I really need to do better than that. Even 10 mpg saves me 30% on gas a year. I can push the truck on flat ground easily in neutral, so I don't think anything is binding up. The truck is in great condition and runs almost perfectly. Here are my thoughts, please weigh in! Maybe I'm missing something else.

1. The rear end is already switched to a 3.73
2. Convert the np203 transfer case to part time with a conversion kit. Awesome transfer case, but I've heard it burns through gas. However, I've heard the conversion (and running it mostly in 2 wheel drive) doesn't even increase mpg that much.
3. Continue to tune my Q-Jet (I just rebuilt it). Maybe buy an air/fuel ratio gauge to get it really dialed in?
4. Switch my Q-Jet to a basic EFI system (I would like to avoid this one)

I love having the 400 transmission, NP203, and original Q-jet. Its about as solid and durable as you can. I'd like to avoid changing it from a stock setup. Thanks!